Introduction

AutoLISP and Visual LISP
AutoLISP Developer's Guide >
Introduction

For years, AutoLISP® has set the standard for customizing AutoCAD®. Now Visual LISP® (VLISP) represents the next generation of LISP for AutoCAD, by adding significantly more capabilities. VLISP extends the language to interface with objects via the Microsoft ActiveX® Automation interface, and enhances the ability of AutoLISP to respond to events through the implementation of reactor functions. As a development tool, VLISP provides a complete, integrated development environment (IDE) that includes a compiler, debugger, and other tools to increase productivity when customizing AutoCAD.

Topics in this section

  • AutoLISP and Visual LISP
  • Using Visual LISP Documentation
  • Related Documents
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AutoLISP and Visual LISP

Introduction
Introduction
What Visual LISP Offers
AutoLISP Developer's Guide > Introduction >
AutoLISP and Visual LISP

AutoLISP is a programming language designed for extending and customizing AutoCAD functionality. It is based on the LISP programming language, whose origins date back to the late 1950s. LISP was originally designed for use in Artificial Intelligence (AI) applications, and is still the basis for many AI applications.

AutoCAD introduced AutoLISP as an application programming interface (API) in Release 2.1, in the mid-1980s. LISP was chosen as the initial AutoCAD API because it was uniquely suited for the unstructured design process of AutoCAD projects, which involved repeatedly trying different solutions to design problems.

Visual LISP (VLISP) is a software tool designed to expedite AutoLISP program development. The VLISP integrated development environment (IDE) provides features to help ease the tasks of source-code creation and modification, program testing, and debugging. In addition, VLISP provides a vehicle for delivering standalone applications written in AutoLISP.

In the past, developing AutoLISP programs for AutoCAD meant supplying your own text editor for writing code, then loading the code into AutoCAD and running it. Debugging your program meant adding statements to print the contents of variables at strategic points in your program. You had to figure out where in your program to do this, and what variables you needed to look at. If you discovered you still didn't have enough information to determine the error, you had to go back and change the code again by adding more debugging points. And finally, when you got the program to work correctly, you needed to either comment out or remove the debugging code you added.

Topics in this section

  • What Visual LISP Offers
  • Working with Visual LISP and AutoCAD


What Visual LISP Offers

AutoLISP and Visual LISP
AutoLISP and Visual LISP
Working with Visual LISP and AutoCAD
AutoLISP Developer's Guide > Introduction > AutoLISP and Visual LISP >
What Visual LISP Offers

During the development cycle of an AutoLISP application or routine, the AutoLISP user performs a number of operations that are not available within the AutoCAD software. Some of these operations—like text editing—are available with other software tools. Others, such as full AutoLISP source-level debugging, are introduced only with VLISP. In VLISP, you perform most of the necessary operations inside a single environment. This permits text editing, program debugging, and interaction with AutoCAD and other applications.

The following are components of the Visual LISP IDE:

  • Syntax Checker recognizes erroneous AutoLISP constructs and improper arguments in calls to built-in functions.
  • File Compiler improves the execution speed and provides a secure and efficient delivery platform.
  • Source Debugger, designed specifically for AutoLISP, supports stepping through AutoLISP source code in one window while simultaneously displaying the results of code execution in an AutoCAD drawing window.
  • Text File Editor uses AutoLISP and DCL color coding, as well as other AutoLISP syntax support features.
  • AutoLISP Formatter restructures programs into an easily readable format.
  • Comprehensive Inspect and Watch features provide convenient access to variable and expression values for data structure browsing and modification. These features may be used to explore AutoLISP data and AutoCAD drawing entities.
  • Context-sensitive Help provides information for AutoLISP functions and a powerful Apropos feature for symbol name search.
  • Project Management system makes it easy to maintain multiple-file applications.
  • Compiled AutoLISP files are packaged into a single module.
  • Desktop Save and Restore capabilities preserve and reuse the windowing environment from any VLISP session.
  • Intelligent Console window introduces a new level of convenience and efficiency for AutoLISP users. The basic functions of the Console correspond to the AutoCAD Text Screen functions and provide a number of interactive features, such as history scrolling and full-input line editing.


Working with Visual LISP and AutoCAD

What Visual LISP Offers
AutoLISP and Visual LISP
Using Visual LISP Documentation
AutoLISP Developer's Guide > Introduction > AutoLISP and Visual LISP >
Working with Visual LISP and AutoCAD

VLISP contains its own set of windows and menus that are distinct from the rest of AutoCAD, but VLISP does not run independently of AutoCAD. Whenever you work in VLISP, AutoCAD must also be running. When you run AutoLISP programs from the VLISP IDE, you will usually need to interact with the AutoCAD graphics or Command windows to respond to program prompts.

If AutoCAD is minimized when VLISP turns control over to it, you must manually restore and activate the AutoCAD window to continue. VLISP will not restore the AutoCAD window for you. Instead, a Visual LISP symbol appears in the VLISP window and remains there until you activate AutoCAD and respond to the prompts at the AutoCAD Command prompt. The Getting Started chapter shows an example of this; see Loading and Running AutoLISP Programs.


Using Visual LISP Documentation

Working with Visual LISP and AutoCAD
Introduction
Related Documents
AutoLISP Developer's Guide > Introduction >
Using Visual LISP Documentation

The AutoLISP Developer's Guide explains how to use the Visual LISP IDE and how to build and run AutoLISP applications. This guide also introduces the constructs of the AutoLISP language.

All users should check the AutoCAD Readme file for notices concerning AutoLISP and Visual LISP. The Readme file is in the AutoCAD Help directory and contains information that became available too late to be included in this manual.

If you have developed AutoLISP applications in earlier releases of AutoCAD, it is important that you refer to the Readme file for information on AutoLISP changes that may affect your applications.

Additional AutoLISP and Visual LISP manuals are available online through the Visual LISP and AutoCAD Help menus:

  • The AutoLISP Reference describes every AutoLISP function and provides examples. Refer to the AutoLISP Reference when you need to look up the syntax of a function or determine what a function returns.
  • The AutoLISP Tutorial contains step-by-step instructions guiding you toward building a working Visual LISP application.

This AutoLISP Developer's Guide assumes you have some experience with AutoCAD and have basic user-level skills with Microsoft® Windows®. Prior experience with AutoLISP is not required.

The AutoLISP Developer's Guide is divided into the following sections:

  • Using the Visual LISP Environment describes how to use VLISP to develop and test AutoLISP programs.
  • Using the AutoLISP Language is a detailed guide describing the elements and structures of the AutoLISP language.
  • Working with Programmable Dialog Boxes describes how to design and implement dialog boxes in your AutoLISP applications.
  • Appendixes includes a function synopsis summarizing AutoLISP functions by category, information on AutoLISP error codes, and a summary of the environment and program options available in Visual LISP.

The following are a few guidelines to help you get the most out of the AutoLISP Developer's Guide:

  • Begin by reading chapter 1, Getting Started. This chapter tells you how to invoke VLISP from AutoCAD, identifies what you'll see when VLISP first starts, and describes how to load and run existing AutoLISP programs from VLISP. Chapter 1 introduces and briefly describes the windows you will be working with in the VLISP IDE. Use this chapter to orient yourself to the VLISP environment.
  • If you do not already know AutoLISP, read all of chapter 8, AutoLISP Basics, and at least browse chapters 9 and 10, Using AutoLISP to Communicate with AutoCAD and Using AutoLISP to Manipulate AutoCAD Objects, respectively. After that, you can either work through the tutorial or read more chapters in the AutoLISP Developer's Guide.
  • To search for a function that meets a particular programming need, refer to AutoLISP Function Synopsis, in this guide.

The following table summarizes the organization of this manual:

Chapter organization
Chapter | Title | Contents
1 | Getting Started | Provides an orientation to Visual LISP.
2 | Developing Programs with Visual LISP | Shows you how to use the VLISP text editor to enter AutoLISP program code, format the code, and check the code for AutoLISP syntax errors. Also shows you how to run the code you've developed from the VLISP editor window.
3 | Debugging Programs | Shows you how to use VLISP to trace program execution, watch the value of variables change during program execution, see the sequence in which expressions are evaluated, and step through program execution one instruction at a time.
4 | Building Applications | Introduces the VLISP file compiler and shows how you can use the VLISP Application Wizard to build standalone applications.
5 | Maintaining Visual LISP Applications | Describes how to define VLISP projects and use them to simplify working with multi-file applications. This chapter also explains compiler optimization features, and how to use them in a project.
6 | Working with ActiveX | Describes how to use ActiveX objects with VLISP, and how to access other applications through ActiveX.
7 | Advanced Topics | Describes how to attach reactors to AutoCAD drawings and objects.
8 | AutoLISP Basics | Introduces basic AutoLISP concepts, such as how to use expressions and variables, handle numbers and strings, display output, build lists, and define functions.
9 | Using AutoLISP to Communicate with AutoCAD | Describes AutoLISP functions that you can use to issue AutoCAD commands and to interact with users in the AutoCAD environment.
10 | Using AutoLISP to Manipulate AutoCAD Objects | Describes AutoLISP functions you can use to manipulate AutoCAD drawing entities, selection sets, extended data, and symbol tables.
11 | Designing Dialog Boxes | Introduces the elements that make up dialog boxes. Explains DCL file structure and syntax, and presents AutoLISP and DCL code that defines and displays a sample dialog box.
12 | Managing Dialog Boxes | Describes how to control dialog boxes with AutoLISP programs.
13 | Programmable Dialog Box Reference | Lists and describes all the DCL tiles and their associated attributes, and summarizes the AutoLISP functions available tor work with programmable dialog boxes.


Related Documents

Using Visual LISP Documentation
Introduction
Using the Visual LISP Environment
AutoLISP Developer's Guide > Introduction >
Related Documents

In addition to the AutoLISP Reference and the AutoLISP Tutorial, several other AutoCAD publications may be required by users building applications with Visual LISP:

  • AutoCAD ActiveX and VBA Reference contains information on accessing ActiveX methods, properties, and objects. If you develop AutoLISP applications that use ActiveX automation to reference AutoCAD objects, you will need to refer to this reference. It is available through the AutoCAD and Visual LISP Help menus.
  • AutoCAD Customization Guide contains basic information on creating customized AutoCAD applications. For example, it includes information on creating customized menus, linetypes, and hatch patterns. The Customization Guide is available through the AutoCAD and Visual LISP Help menus.
  • The DXF Reference describes drawing interchange format (DXFTM) and the DXF group codes that identify attributes of AutoCAD objects. You may need to refer to the DXF Reference when working with association lists describing entity data. The DXF Reference is available through the AutoCAD and Visual LISP Help menus.
  • The ObjectARX Reference contains information on using ObjectARX® to develop customized AutoCAD applications. AutoCAD reactor functionality is implemented through ObjectARX. If you develop AutoLISP applications that implement reactor functions, you may want to refer to this manual.

    The ObjectARX Reference is not included when you install AutoCAD. To obtain the manual, download the ObjectARX SDK (Software Development Kit) from the www.autodesk.com.


Using the Visual LISP Environment

Related Documents
Getting Started
AutoLISP Developer's Guide >
Using the Visual LISP Environment

Topics in this section

  • Getting Started

    You can use Visual LISP to increase your productivity by compiling programs, stepping through code, and debugging.

  • Developing Programs with Visual LISP

    With Visual LISP, you can format your code and automatically detect syntax errors.

  • Debugging Programs

    To debug a program, you can trace execution, trace the values of variables during execution, and view the sequence in which expressions are evaluated.

  • Building Applications

    You can compile your program files and create a single executable module that you can distribute to users.

  • Maintaining Visual LISP Applications

    You can maintain large programs by creating a Visual LISP project and optimizing code.

  • Working with ActiveX

    With Visual LISP, you can access the AutoCAD object model.

  • Advanced Topics

    You can use reactors for event notification.


Getting Started

Using the Visual LISP Environment
Using the Visual LISP Environment
Starting Visual LISP
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Getting Started

You can use Visual LISP to increase your productivity by compiling programs, stepping through code, and debugging.

This chapter introduces you to the look and feel of the Visual LISP® interactive development environment (IDE), and shows you how to run AutoLISP® programs in Visual LISP.

Topics in this section

  • Starting Visual LISP
  • Exploring the Visual LISP User Interface
  • Touring the Visual LISP Menus
  • Understanding the Console Window
  • Understanding the Visual LISP Text Editor
  • Loading and Running AutoLISP Programs
  • Exiting Visual LISP


Starting Visual LISP

Getting Started
Getting Started
Exploring the Visual LISP User Interface
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Starting Visual LISP

The Visual LISP (VLISP) interactive development environment runs in a separate set of windows from the rest of AutoCAD® . You must explicitly start VLISP to work in the interactive development environment.

To start Visual LISP

  1. Start AutoCAD.
  2. Choose Tools [image] AutoLISP [image] Visual LISP Editor from the AutoCAD menu, or enter the following at the Command prompt:
    vlisp

You can use either the menu or the vlisp command to return to the VLISP IDE at any time.

Note that AutoCAD also recognizes the vlide command to start or return to Visual LISP. This command name stands for “Visual LISP interactive development environment.” AutoCAD issues the vlide command to call VLISP, and as a result you may sometimes see “VLIDE” displayed in the AutoCAD Command window.


Exploring the Visual LISP User Interface

Starting Visual LISP
Getting Started
Introducing the Visual LISP Text Editor
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Exploring the Visual LISP User Interface

When you first start Visual LISP, the following components are displayed:

Menu

You can issue VLISP commands by choosing from the various menu items. If you highlight an item on a menu, VLISP displays a brief description of the command's function in the status bar at the bottom of the screen.

Toolbars

Click toolbar buttons to issue VLISP commands quickly. There are five toolbars—Debug, Edit, Find, Inspect, and Run—each representing a distinct functional group of VLISP commands. You can execute many, but not all, menu commands from the toolbars. If you move your mouse pointer over a toolbar button and leave it there for a couple of seconds, VLISP displays a tooltip indicating the function of the button. A more descriptive explanation appears in the status bar at the bottom of the VLISP screen.

Console Window

This is a separate, scrollable window within the main VLISP window. In the Console window, you can type AutoLISP commands, similar to the way you do in the AutoCAD Command window. You can also issue many Visual LISP commands from this window, instead of using the menu or toolbars. See Understanding the Console Window for more information on the Console window.

Status Bar

The information displayed in the status bar located at the bottom of the screen varies according to what you are doing in VLISP.

You may also see a minimized Trace window. During startup, this window contains informational messages about the current release of VLISP, and may contain additional information if VLISP encounters errors during startup.

Topics in this section

  • Introducing the Visual LISP Text Editor
  • Other Visual LISP Windows


Introducing the Visual LISP Text Editor

Exploring the Visual LISP User Interface
Exploring the Visual LISP User Interface
Other Visual LISP Windows
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started > Exploring the Visual LISP User Interface >
Introducing the Visual LISP Text Editor

You will spend much of your time in VLISP creating or modifying AutoLISP programs. VLISP comes with an integrated text editor for you to use with AutoLISP code.

To see how the text editor window displays code, open a sample AutoLISP program. Begin with the drawline.lsp file provided with VLISP.

NoteThe sample files are only included in your installation if you chose a Full installation, or if you chose a Custom installation and selected the Visual LISP Samples item. If you previously installed AutoCAD and did not install the samples, rerun the install, choose Custom, and select the Visual LISP Samples item.

To view a LISP program in the VLISP text editor

  1. From the VLISP menu, choose File [image] Open File.
  2. In the Open File dialog box, select the Sample\VisualLISP folder, which is in your AutoCAD installation directory.
  3. Double-click the drawline.lsp file.

    VLISP opens the file in a new window—the text editor window—and displays the name of the file in the status bar. If you make a change to the text in the editor window, or add new text, VLISP places an asterisk (*) next to the file name in the status bar. The asterisk remains next to that file name until you either save your changes or close the file.

    You can work on more than one file at a time. Each time you open a file, VLISP displays the file in a new text editor window.


Other Visual LISP Windows

Introducing the Visual LISP Text Editor
Exploring the Visual LISP User Interface
Touring the Visual LISP Menus
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started > Exploring the Visual LISP User Interface >
Other Visual LISP Windows

VLISP displays some output in the Console window, but several VLISP functions create their own windows in which to display results. For example, when you trace the sequence of events during a running AutoLISP program, the Trace function opens a window and displays program events. You cannot enter text in these output windows, but you can copy text from them and paste the text into the editor or Console windows.


Touring the Visual LISP Menus

Other Visual LISP Windows
Getting Started
Variable Menu Contents
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Touring the Visual LISP Menus

You can issue VLISP commands by choosing from the various menu items. For example, from the File menu you can create a new AutoLISP program file, select an existing program file to edit, and print the file you're editing.

Topics in this section

  • Variable Menu Contents
  • Visual LISP Menu Summary


Variable Menu Contents

Touring the Visual LISP Menus
Touring the Visual LISP Menus
Visual LISP Menu Summary
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started > Touring the Visual LISP Menus >
Variable Menu Contents

Menu contents may vary depending on which VLISP window (for example, text editor, Console) is active. To activate a different window, click in the window's title bar, or in any empty area of that window.

As an example, click in the text editor window containing the drawline.lsp file, then choose Edit from the VLISP menu. You'll see the following list:

Note that the last items on the menu are Parentheses Matching and Extra Commands.

Now click in the title bar of the VLISP Console window, then select the Edit menu item again:

Notice that Extra Commands is no longer the last item on the menu. Parentheses Matching is followed by two new items, Console History Up and Console History Down; these items apply only to a Console window.


Visual LISP Menu Summary

Variable Menu Contents
Touring the Visual LISP Menus
Understanding the Console Window
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started > Touring the Visual LISP Menus >
Visual LISP Menu Summary

The following table summarizes the VLISP menu items.

Visual LISP menu items
Menu item | Uses
File | Create a new AutoLISP program file for editing, open an existing file, save changes to program files, build Visual LISP application files, and print program files.
Edit | Copy and paste text, undo the last change you made to text (or undo the last command entered in the Console window), select text in the VLISP editor or Console windows, match parentheses in expressions, and redisplay previous commands entered in the Console window. See the chapter titled Developing Programs with Visual LISP for more information on Edit features.
Search | Find and replace text strings, set bookmarks, and navigate among bookmarked text. See Using the Text Editor for information on these topics.
View | Find and display the value of variables and symbols in your AutoLISP code. For more information on this topic, see chapter 3, Debugging Programs.
Project | Work with projects and compile programs. See Managing Multiple LISP Files, and Compiling and Linking Programs for information on these topics.
Debug | Set and remove breakpoints in your program and step through program execution one expression at a time. You can then check the state of variables and the results of expressions. See chapter 3, Debugging Programs, for more information on these features.
Tools | Set VLISP options for text formatting and various environment options, such as the placement of windows and toolbars.
Window | Organize the windows currently displayed in your VLISP session, or activate another VLISP or AutoCAD window.
Help | Display Help.


Understanding the Console Window

Visual LISP Menu Summary
Getting Started
Understanding the Visual LISP Text Editor
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Understanding the Console Window

From the VLISP Console window, you can enter and run AutoLISP commands and see the results. This is similar to what you can do in the AutoCAD Command window, but there are a few differences—some subtle—in how you accomplish the same task in these two windows. For example, to display the current value of an AutoLISP variable in VLISP, you simply type the variable name in the Console window and press ENTER. To view the value of a variable in AutoCAD, you must precede the variable name with an exclamation point (!) when you type it in the Command window.

The Console window is also where VLISP displays AutoLISP diagnostic messages and the results of many AutoLISP functions. For example, output from the print and princ functions is displayed in the Console window. You can scroll through the Console window to view previously entered text and output.

For a description of VLISP Console window features, see Using the Console Window. The following is a brief summary of these features:

  • Evaluating AutoLISP expressions and displaying the return values from those expressions.
  • Entering AutoLISP expressions on multiple lines by pressing CTRL + ENTER to continue on the next line.
  • Evaluating multiple expressions at one time.
  • Copying and transferring text between the Console and text editor windows. Most text editor commands are also available in the Console window.
  • Retrieving previous commands entered in the Console by pressing TAB. You can press TAB repeatedly to retrieve earlier commands. Press SHIFT + TAB to reverse the direction of command retrieval.
  • Performing an associative search through the input history by pressing TAB. For example, if you begin an expression with (+ and then press TAB, VLISP retrieves the last command you entered that begins with (+. To reverse the direction of the search, press SHIFT + TAB.
  • Pressing ESC clears any text following the Console prompt.
  • Pressing SHIFT + ESC leaves the text you entered at the Console prompt without evaluating the text, and displays a new Console prompt.
  • Right-clicking or pressing SHIFT + F10 anywhere in the Console window displays a menu of VLISP commands and options. For example, you can use this feature to copy and paste text in the Console command line, search for text, and initiate VLISP debugging features.

Note that if you type text at the Console prompt but switch to the AutoCAD window before pressing ENTER, the text will no longer be at the prompt when you return to the VLISP window.


Understanding the Visual LISP Text Editor

Understanding the Console Window
Getting Started
Loading and Running AutoLISP Programs
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Understanding the Visual LISP Text Editor

The VLISP text editor is much more than a writing tool, it's a central component of the VLISP programming environment. To appreciate the versatility and value of the VLISP text editor, you need to be familiar with the AutoLISP language. If you are not yet familiar with AutoLISP, you can learn the basics in chapter 8, AutoLISP Basics and find additional information in chapter 9, Using AutoLISP to Communicate with AutoCAD and chapter 10, Using AutoLISP to Manipulate AutoCAD Objects

Here are some of the major features of the text editor:

Color Coding of Files

The text editor identifies different parts of an AutoLISP program and assigns distinct colors to them. This allows you to find program components easily such as function calls and variable names, and helps you find typographical errors.

Formatting of Text

The text editor can format AutoLISP code for you, making the code easier to read. You can choose from a number of different formatting styles.

Parenthesis Matching

AutoLISP code contains many parentheses, and the editor helps you detect missing parentheses by finding the close parenthesis that goes with an open parenthesis.

Execution of AutoLISP Expressions

You can test expressions and lines of code without leaving the text editor.

Multiple File Searching

The text editor can search for a word or expression in several files with a single command.

Syntax Checking of AutoLISP Code

The text editor can evaluate AutoLISP code and highlight syntax errors.

Details on using the VLISP text editor begin with Using the Text Editor.


Loading and Running AutoLISP Programs

Understanding the Visual LISP Text Editor
Getting Started
Running Selected Lines of Code
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Loading and Running AutoLISP Programs

Once you have opened an AutoLISP program file in the VLISP text editor, you can load and run it. Loading is the process by which functions in a program file are made available to the VLISP command interpreter. You can try this with the drawline.lsp sample program.

To load and run a program in a Visual LISP text editor window

  1. Make sure the text editor window containing the drawline.lsp program is active. If you are not sure whether the window is active, click anywhere in the window to activate it.
  2. Choose the Load Active Edit Window button from the Run toolbar, or choose Tools [image] Load Text in Editor from the VLISP menu.

    VLISP responds by displaying a message in the Console window indicating it has loaded the program.

  3. Run the drawline function from the Console prompt by entering the function name in parentheses, then pressing ENTER:
    _$ (drawline)

    The drawline function will ask you to specify two points, and will then draw a straight line between those points. When drawline asks for user input, VLISP turns control over to AutoCAD to prompt you for the points. What you see next depends on whether or not the AutoCAD windows are currently displayed on your desktop. If AutoCAD is already on your desktop, you'll see the AutoCAD windows. But if AutoCAD is currently minimized on your desktop, the windows won't automatically be restored and displayed. Instead, VLISP remains visible and your mouse pointer changes to a VLISP symbol.

    This symbol indicates that the VLISP window is no longer active. If this is the case, you must manually switch to the AutoCAD window. Click the AutoCAD icon on the Windows task bar to activate AutoCAD.

  4. Respond to the prompts by specifying points in the graphics window or on the Command line.

    After you respond to the prompts, control returns to VLISP and you will once again see the VLISP window.

    When you enter commands in the VLISP Console window or run a program loaded from the text editor, you may be frequently switching back and forth between the VLISP and AutoCAD windows. Aside from using the standard Windows methods of switching between windows, you can activate the AutoCAD window by choosing Window [image] Activate AutoCAD from the VLISP menu, or by clicking the Activate AutoCAD button on the Run toolbar. If you are in AutoCAD and want to return to the VLISP environment, you can enter vlisp at the Command prompt, or choose Tools [image] AutoLISP [image] Visual LISP Editor from the AutoCAD menu.

Topics in this section

  • Running Selected Lines of Code
  • Using Extended AutoLISP Functions


Running Selected Lines of Code

Loading and Running AutoLISP Programs
Loading and Running AutoLISP Programs
Using Extended AutoLISP Functions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started > Loading and Running AutoLISP Programs >
Running Selected Lines of Code

With VLISP, you can select lines of code in the text editor window and run only the selected code, instead of the whole program.

To run selected lines of AutoLISP code in a Visual LISP editor window

  1. Using the drawline.lsp program as an example, highlight the following lines of code:
    (setq pt1(getpoint "\nEnter the start point for the line: ")
          pt2(getpoint pt1 "\nEnter the end point for the line: "))
  2. Choose the Load Selection button on the Run toolbar.

    VLISP immediately runs the code and switches control to AutoCAD to prompt you for input.


Using Extended AutoLISP Functions

Running Selected Lines of Code
Loading and Running AutoLISP Programs
Exiting Visual LISP
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started > Loading and Running AutoLISP Programs >
Using Extended AutoLISP Functions

VLISP provides some extensions to the AutoLISP language that are not loaded automatically when you start AutoCAD. These functions have names that begin with vla-, vlax-, and vlr. The vla- functions implement ActiveX® support in AutoLISP (described in Working with ActiveX). The vlax- functions provide ActiveX utility and data conversion functions, dictionary handling functions, and curve measurement functions. The vlr- functions provide support for AutoCAD reactors. Before you can use any of these functions, you need to load the AutoLISP extensions with the following function call:

(vl-load-com)

This function first checks whether or not the AutoLISP extensions are already loaded. If the AutoLISP extensions are loaded, function does nothing; otherwise it loads the extensions.

If you're using the VLISP interactive development environment to develop code, chances are you'll want to use the AutoLISP extensions at some point. It's a good practice to issue vl-load-com when you start VLISP, or to include a call to the function in your acaddoc.lsp file, so that it loads automatically. But if you write programs that use any of the extended AutoLISP functions, you need to call vl-load-com in those programs to ensure that the functions are available to other users running your code.


Exiting Visual LISP

Using Extended AutoLISP Functions
Getting Started
Developing Programs with Visual LISP
AutoLISP Developer's Guide > Using the Visual LISP Environment > Getting Started >
Exiting Visual LISP

When you are finished with your VLISP session, you can close the program by either choosing Exit from the File menu or clicking the Windows Close button. Note that AutoCAD does not completely unload VLISP but merely closes all VLISP windows.

Upon exiting AutoCAD, if you have made any changes to the code in any VLISP text editor window and have not saved those changes, you will be asked if you want to save your changes. You can either save all the changes you've made by choosing Yes, or save none of the changes by choosing No.

VLISP retains its state when you exit. The next time you start a VLISP session, VLISP automatically opens whichever files and windows were open when you last exited.


Developing Programs with Visual LISP

Exiting Visual LISP
Using the Visual LISP Environment
Getting Organized
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Developing Programs with Visual LISP

With Visual LISP, you can format your code and automatically detect syntax errors.

Visual LISP® provides many tools and features that help you develop AutoLISP® programs. This chapter describes the features that help you during the coding phase of program development. These features format AutoLISP code to improve readability and help you detect syntax errors in your code.

Topics in this section

  • Getting Organized
  • Using the Console Window
  • Using the Text Editor
  • Using Console and Editor Coding Aids
  • Formatting Code with Visual LISP
  • Checking for Syntax Errors


Getting Organized

Developing Programs with Visual LISP
Developing Programs with Visual LISP
Using the Console Window
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP >
Getting Organized

To develop an AutoLISP program with VLISP you must perform the following steps:

  • Think about which tasks you want to accomplish with your program, and how to approach those tasks.
  • Design the program.
  • Write the code.
  • Format the code for readability.
  • Check for errors in the program.
  • Test and debug the program.

This chapter provides you with information to help you accomplish writing, formatting, and checking tasks. The Debugging Programs chapter describes the debugging features of VLISP. The Building Applications and Maintaining Visual LISP Applications chapters describe how to package your programs into applications that can be run by other users, and how to organize application components to facilitate future updates.


Using the Console Window

Getting Organized
Developing Programs with Visual LISP
Understanding Console Behavior
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP >
Using the Console Window

Most programming in VLISP takes place within the confines of the VLISP text editor, but the ability to program interactively with AutoLISP provides some unique advantages to the development process. In the VLISP Console window you can enter AutoLISP code and immediately see the results of executing that code.

Enter text in the Console window following the Console prompt, which looks like the following:

_$

VLISP saves the text you enter and any output from executing the text. You can then scroll through the Console window and see what transpired. You can copy any text in the window and paste it at the Console prompt or in another Windows application.

Topics in this section

  • Understanding Console Behavior
  • Using the Console Window with Multiple Drawings
  • Using the Console Shortcut Menu
  • Logging Console Window Activity


Understanding Console Behavior

Using the Console Window
Using the Console Window
Using the Console Window History
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Console Window >
Understanding Console Behavior

The VLISP Console window is similar in some respects to the AutoCAD® Command window, but it provides many more features. Although the Console window and the AutoCAD Command window provide similar capabilities, you don't always use the same process to accomplish identical tasks. For example, to display the current value of an AutoLISP variable in VLISP, you simply type the variable name in the Console window and press ENTER. To view the value of a variable in AutoCAD, you must precede the variable name with an exclamation point (!) when you enter it at the AutoCAD Command prompt.

Unlike the AutoCAD Command window, where pressing SPACEBAR causes expression evaluation, text input at the VLISP Console prompt is not processed until you press ENTER. This permits you to do the following in the Console window:

  • Continue an AutoLISP expression on a new line. To continue entering an expression on a new line, press CTRL + ENTER at the point you want to continue.
  • Input more than one expression before pressing ENTER. VLISP evaluates each expression before returning a value to the Console window.
  • If you select text in the Console window (for example, the result of a previous command or a previously entered expression), then press ENTER. VLISP copies the selected text at the Console prompt.

The VLISP Console window and the AutoCAD Command window differ in the way they process the SPACEBAR and TAB keys. In the VLISP Console window, a space plays no special role and serves only as a separator. In the AutoCAD Command window, pressing the SPACEBAR outside an expression causes AutoCAD to process the text immediately, as if you had pressed ENTER.

Topics in this section

  • Using the Console Window History
  • Interrupting Commands and Clearing the Console Input Area


Using the Console Window History

Understanding Console Behavior
Understanding Console Behavior
Interrupting Commands and Clearing the Console Input Area
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Console Window > Understanding Console Behavior >
Using the Console Window History

You can retrieve text you previously entered in the Console window by pressing TAB while at the Console prompt. Each time you press TAB, the previously entered text replaces the text at the Console prompt. You can repeatedly press TAB until you cycle through all the text entered at the Console prompt during your VLISP session. After you've scrolled to the first entered line, VLISP starts again by retrieving the last command entered in the Console window, and the cycle repeats. Press SHIFT + TAB to scroll the input history in the opposite direction.

For example, assume you entered the following commands at the Console prompt:

(setq origin (getpoint "\nOrigin of inyn sign: "))
(setq radius (getdist "\nRadius of inyn sign: " origin))
(setq half-r (/ radius 2))
(setq origin-x (car origin))
(command "_.CIRCLE" origin radius)

To retrieve commands entered in the Console window

  1. Press TAB once. VLISP retrieves the last command entered and places it at the Console prompt:
    _$ (command "_.CIRCLE" origin radius)
  2. Press TAB again. The following command displays at the Console prompt:
    _$  (setq origin-x (car origin))
  3. Press TAB again. VLISP displays the following command:
    _$  (setq half-r (/ radius 2))
  4. Now press SHIFT + TAB. VLISP reverses direction and retrieves the command you entered after the previous command:
    _$ (setq origin-x (car origin))
  5. Press SHIFT + TAB again. VLISP displays the following command:
    _$ (command "_.CIRCLE" origin radius)

    This was the last command you entered at the Console prompt.

  6. Press SHIFT + TAB again. Because the previous command retrieved was the last command you entered during this VLISP session, VLISP starts again by retrieving the first command you entered in the Console window:
    _$ (setq origin (getpoint "\nOrigin of inyn sign: "))

    Note that if you enter the same expression more than once, it appears only once as you cycle through the Console window input history.

    You can perform an associative search in the input history to retrieve a specific command that you previously entered.

To perform an associative search of the Console input history

  1. Enter the text you want to locate. For example, enter (command at the Console prompt:
    _$ (command
  2. Press TAB. VLISP searches for the last text you entered that began with (command:
    _$ (command "_.CIRCLE" origin radius)

    If VLISP does not find a match, it does nothing (except possibly emit a beep). Press SHIFT + TAB to reverse the direction of the associative search and find progressively less-recent inputs.


Interrupting Commands and Clearing the Console Input Area

Using the Console Window History
Understanding Console Behavior
Using the Console Window with Multiple Drawings
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Console Window > Understanding Console Behavior >
Interrupting Commands and Clearing the Console Input Area

To interrupt a command entered in the Console window, press SHIFT + ESC. For example, if you enter an invalid function call like the following:

_$ ((setq origin-x (car origin)
((_>

Pressing SHIFT + ESC interrupts the command, and VLISP displays an “input discarded” message like the following:

((_>  ; <input discarded>
_$

(Note that in this example, you can also complete the command by entering the missing close parentheses.)

If you type text at the Console prompt, but do not press ENTER, then pressing ESC clears the text you typed. If you press SHIFT + ESC, VLISP leaves the text you entered in the Console window but displays a new prompt without evaluating the text.

If you type part of a command at the Console prompt, but activate the AutoCAD window before pressing ENTER, VLISP displays a new prompt when you next activate the VLISP window. The text you typed is visible in the Console window history, so you can copy and paste it, but you cannot retrieve the text by pressing TAB, because it was not added to the Console history buffer.


Using the Console Window with Multiple Drawings

Interrupting Commands and Clearing the Console Input Area
Using the Console Window
Using the Console Shortcut Menu
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Console Window >
Using the Console Window with Multiple Drawings

There is a single Console window for all open AutoCAD drawing documents. When you scroll through the Console window, you see commands entered in all document contexts. This differs from the AutoCAD Command window, which shows only the commands issued against the current drawing. In other words, each AutoCAD drawing has its own Command window, but all drawings share the same VLISP Console prompt.

VLISP automatically switches context when you change the active drawing document in AutoCAD. The active document in AutoCAD is always the active document in VLISP. Commands entered in the VLISP Console window always apply to the active document. The title bar of the VLISP window contains the name of the active drawing document.


Using the Console Shortcut Menu

Using the Console Window with Multiple Drawings
Using the Console Window
Logging Console Window Activity
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Console Window >
Using the Console Shortcut Menu

The most important functions needed when working with the VLISP Console window are combined into a shortcut menu for fast access. Right-click anywhere in the Console window or press SHIFT + F10 to display the shortcut menu.

Depending on whether there is text selected in the Console window and depending on the cursor position, some commands may not be appropriate at the moment and cannot be activated from the shortcut menu. The following table summarizes the commands that may be available from the Console window shortcut menu.

Console window shortcut menu commands
Command | Action
Cut | Removes the selected text from the Console window and moves it to the Windows Clipboard
Copy | Copies the selected text to the Clipboard
Paste | Pastes the Clipboard contents to the cursor location
Clear Console window | Empties the Console window
Find | Finds specified text in the Console window
Inspect | Opens the Inspect dialog box
Add Watch | Opens the Watch window
Apropos window | Opens the Apropos window
Symbol Service | Opens the Symbol Service dialog box
Undo | Reverses the last operation
Redo | Reverses the effects of the previous Undo
AutoCAD Mode | Transfers all input to the AutoCAD command line for evaluation
Toggle Console Log | Copies Console window output to the log file

Note also that you can cut and paste text between the VLISP Console window and the AutoCAD Command window.


Logging Console Window Activity

Using the Console Shortcut Menu
Using the Console Window
Using the Text Editor
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Console Window >
Logging Console Window Activity

You can keep a record of all Console window activity by logging the activity in a file. Later, you can view the file and review the activity that occurred in the Console window.

To control Console logging activity

  1. Create a log file by choosing File [image] Toggle Console Log from the VLISP menu. Note that the Console window must be active for the Toggle Console Log option to be available.
  2. Choose a directory for the log file and specify a file name for the log.

    If the file already exists, VLISP displays an alert box that asks if you want to append the current log to the existing file.

    If you choose Yes, VLISP appends future Console window information to the existing contents of the file. If you choose No, VLISP overwrites the file.

  3. To close the log file and quit the logging process, choose Toggle Console Log from the File menu again.

The state of Console window logging is indicated in the Console window's title bar. If logging is in effect, VLISP displays the name of the log file in the title bar. If logging is off, no file name appears in the title bar.

If you do not close the log file before exiting VLISP, it closes the log file automatically upon exit. After a log file is closed, you can view its contents with any text editor, such as the VLISP text editor.


Using the Text Editor

Logging Console Window Activity
Developing Programs with Visual LISP
Editing a File
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP >
Using the Text Editor

If you just need to run a few simple AutoLISP expressions, entering the expressions in the VLISP System Console may suffice. For anything more than that, however, you will need to use the VLISP text editor and save your AutoLISP code in a file.

The text editor is a basic component of VLISP. It is easy to use and, if you have some experience using Windows, you can begin using it after a quick review of this chapter.

The VLISP text editor has a number of features designed to support AutoLISP programming, such as selecting of complete AutoLISP expressions, matching of balanced parentheses, syntax coloring, and executing AutoLISP expressions without leaving the editor window. Most text editor commands can be called from the menu bar, and some of the most frequently used commands are also available from toolbar push buttons.

Topics in this section

  • Editing a File
  • Using the Text Editor Shortcut Menu
  • Using Keyboard Shortcuts in the Text Editor
  • Moving and Copying Text
  • Searching for Text
  • Bookmarking Text


Editing a File

Using the Text Editor
Using the Text Editor
Undoing Your Last Change
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor >
Editing a File

To open a new file in the VLISP text editor, choose File [image] New File from the menu bar. An empty editor window appears on the screen, and you can begin entering text.

To start a new line, press ENTER. The text editor does not wrap your text when it reaches the end of the visible text editor window, so everything you type goes on the same line until you press ENTER.

You can indent lines of text manually, but VLISP automatically formats code for you as you enter new lines of code. You can also copy text from another file and have VLISP format the block of text you add. See Formatting Code with Visual LISP for details on using the VLISP code formatting features.

Topics in this section

  • Undoing Your Last Change
  • Creating Automatic Backup Files
  • Restoring from a Backup File
  • Editing an Existing File


Undoing Your Last Change

Editing a File
Editing a File
Creating Automatic Backup Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Editing a File >
Undoing Your Last Change

You can reverse your last edit action by choosing Edit [image] Undo from the VLISP menu bar. You can undo a virtually unlimited number of changes, back to the point at which you last saved the file.

To reverse the effects of the Undo command, choose Edit [image] Redo from the menu. Redo only works if you issue it immediately after Undo.


Creating Automatic Backup Files

Undoing Your Last Change
Editing a File
Restoring from a Backup File
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Editing a File >
Creating Automatic Backup Files

VLISP supports the automatic creation of backup copies of files loaded by the text editor. The actual backup creation occurs when you save the file for the first time. Backup files have the same name as your original file, except the file extension begins with an underscore (_) and is followed by the first two characters of the original extension. For example, the backup file for drawline.lsp would be drawline._ls.

Automatic creation of backup files is an option you can set by choosing Tools [image] Environment Options [image] General Options. Choose the Editor option labeled Backup the File Edited on First Save to turn on automatic backup. By default, this option is already selected when you first install VLISP.


Restoring from a Backup File

Creating Automatic Backup Files
Editing a File
Editing an Existing File
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Editing a File >
Restoring from a Backup File

If a backup file exists, you can restore the file you are editing to its original content, reversing all the changes you made. From the File menu, choose Revert to restore the file. If there is no backup file for the text in the editor window, VLISP displays an error message.


Editing an Existing File

Restoring from a Backup File
Editing a File
Using the Text Editor Shortcut Menu
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Editing a File >
Editing an Existing File

Choose File [image] Open from the VLISP menu to open an existing file. VLISP opens a new text editor window for the file you select. You can open any number of files and work on them simultaneously. VLISP places each file in its own editor window.

NoteIf you select text in any VLISP window before choosing File [image] Open, the selected text is placed in the File name field of the Open dialog box.

When you exit VLISP, it notes which files are open and saves this information for your next VLISP session. The next time you start VLISP, it automatically opens the files for you.


Using the Text Editor Shortcut Menu

Editing an Existing File
Using the Text Editor
Using Keyboard Shortcuts in the Text Editor
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor >
Using the Text Editor Shortcut Menu

Right-clicking your mouse in an active VLISP text editor window brings up a shortcut menu for quick access to frequently used commands. Depending on whether there is text highlighted in the editor window and depending on the position of the cursor, some commands on the shortcut menu may be inactive. The following table summarizes the editor shortcut commands:

Text editor window shortcut menu commands
Command | Action
Cut | Moves the selected text to the Clipboard
Copy | Copies the selected text to the Clipboard
Paste | Pastes the Clipboard contents to the cursor position
Find | Finds the specified text in one or more editor windows
Go to Last Edited | Moves the cursor to the position you last edited
Toggle Breakpoint | Sets a breakpoint at the cursor position, or removes a breakpoint if one is set currently at that position
Inspect | Opens the Inspect dialog box
Add Watch | Opens the Watch window
Apropos window | Opens the Apropos window
Symbol Service | Opens the Symbol Service dialog box
Undo | Reverses the last operation
Redo | Reverses the effects of the previous Undo


Using Keyboard Shortcuts in the Text Editor

Using the Text Editor Shortcut Menu
Using the Text Editor
Correcting Text
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor >
Using Keyboard Shortcuts in the Text Editor

The VLISP text editor provides numerous keyboard shortcuts you can use instead of menu selections and mouse clicks.

Topics in this section

  • Correcting Text
  • Selecting Text
  • Navigation Shortcuts
  • Indenting Shortcuts


Correcting Text

Using Keyboard Shortcuts in the Text Editor
Using Keyboard Shortcuts in the Text Editor
Selecting Text
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Using Keyboard Shortcuts in the Text Editor >
Correcting Text

You can delete words or lines using the following shortcuts:

Text correction shortcut keys
To | Press
Erase a word to the left of the cursor | CTRL + BACKSPACE
Erase a word to the right of the cursor | SHIFT + BACKSPACE
Delete characters from the cursor position to the end of the current line | CTRL+E then press E

You can also can use the overstrike mode to insert text. Overstrike mode is toggled on and off by pressing INSERT. When in overstrike mode, each character you type replaces existing text. The cursor changes shape from vertical to horizontal when in overstrike mode.


Selecting Text

Correcting Text
Using Keyboard Shortcuts in the Text Editor
Navigation Shortcuts
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Using Keyboard Shortcuts in the Text Editor >
Selecting Text

The simplest method to select text is to double-click your left mouse button. The amount of text selected depends on the location of your cursor.

  • If the cursor immediately precedes an open parenthesis, VLISP selects all the following text up to the matching close parenthesis.
  • If the cursor immediately follows a close parenthesis, VLISP selects all preceding text up to the matching open parenthesis.
  • If the cursor immediately precedes or follows a word, or is within a word, VLISP selects that word.

To select specific text, press and hold the SHIFT key while pressing the arrow keys on the keyboard. Other keyboard methods of text selection are listed in the following table:

Text selection shortcut keys
To | Press
Expand the selection to the next line | SHIFT+DOWN ARROW
Expand the selection to the previous line | SHIFT+UP ARROW
Expand the selection to the end of the line | SHIFT+END
Expand the selection to the beginning of the line | SHIFT+HOME
Expand the selection down one window, or abandon selection of the next window, if it is currently selected | SHIFT+PAGEDOWN
Expand the selection up one window, or abandon selection of the previous window, if it is currently selected | SHIFT+PAGEUP
Expand the selection to the next word, or abandon selection of the next word, if it is currently selected | CTRL+SHIFT+RIGHT ARROW
Expand the selection to the previous word, or abandon selection of the previous word, if it is currently selected | CTRL+SHIFT+LEFT ARROW
Expand the selection up to the matching left parenthesis | CTRL+SHIFT+[
Expand the selection up to the matching right parenthesis | CTRL+SHIFT+]
Move the cursor to the other side of the selection | ALT+ENTER


Navigation Shortcuts

Selecting Text
Using Keyboard Shortcuts in the Text Editor
Indenting Shortcuts
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Using Keyboard Shortcuts in the Text Editor >
Navigation Shortcuts

In addition to using the cursor arrow keys, you can use the following VLISP editor shortcuts to navigate through your text:

Navigation shortcut keys
To move | Press
One word to the left | CTRL+LEFT ARROW
One word to the right | CTRL+RIGHT ARROW
To the end of a line | END
To the beginning of a line | HOME
Down one window | PAGEDOWN
Up one window | PAGEUP
To the end of a document | CTRL+END
To the start of a document | CTRL+HOME
To the matching left parenthesis | CTRL+[
To the matching right parenthesis | CTRL+]


Indenting Shortcuts

Navigation Shortcuts
Using Keyboard Shortcuts in the Text Editor
Moving and Copying Text
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Using Keyboard Shortcuts in the Text Editor >
Indenting Shortcuts

Most indenting of program code is best handled by the VLISP automatic code formatting and Smart Indent features, and by customizing the formatter's options (see Formatting Code with Visual LISP). But there are some things you may want to do by yourself.

To indent selected lines of code, press TAB or press CTRL + E, and then choose Indent Block. VLISP inserts a TAB character at the beginning of each line you selected. You can control the indent amount of the TAB character by choosing Tools [image] Window Attributes [image] Configure Current and setting the Tab Width value. You can also use the following keyboard shortcuts to adjust the indentation of text.

Code indentation shortcuts
To | Do
Adjust the indent of the current selection to the preceding AutoLISP text. | Press SHIFT+TAB
Clear trailing SPACE and TAB characters, insert a new line, and indent at the level of the previous non-empty line. | Press SHIFT+ENTER
Insert a new line without clearing trailing SPACE and TAB characters of the current line. | Press CTRL+ENTER


Moving and Copying Text

Indenting Shortcuts
Using the Text Editor
Searching for Text
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor >
Moving and Copying Text

In addition to using the standard Windows Cut, Copy, and Paste functions, the VLISP text editor allows you to drag text from one location to another within the edit window.

To move text by dragging

  1. Select the text you want to move.
  2. Point anywhere inside the selected area, and press and hold the left mouse button.
  3. Drag the text to the new location.
  4. Release the mouse button.

To copy the text instead of moving it, follow the same steps, but press CTRL before releasing the mouse button in step 4.

You can also take selected text and copy it into a new file. With the text selected, press CTRL + E to display a list of options, and choose Save Block As. VLISP replies by displaying a dialog box for you to specify where you want to save the text.

VLISP uses the Windows Clipboard for all cut and copy operations. Therefore, you can exchange text with any other Windows application that supports these functions. This also means you can copy and paste text between the text editor and the VLISP Console window.

Remember that immediately after moving or copying text, you can change your mind and reverse the action, using the Undo function.


Searching for Text

Moving and Copying Text
Using the Text Editor
Choosing Search Options
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor >
Searching for Text

The VLISP text editor has extensive text-searching capabilities. From the Search menu, choose Find to begin a search, or choose the Find toolbar button. VLISP displays the Find dialog box.

In the Find What data entry field, type the character string you want to locate. If there is text selected when you enter the Find command, this text is automatically placed in the Find What field.

Choose Find to start the search. When searching through a single file, press F3 to search for the next occurrence of your search string. Choose Cancel to end the search.

When searching through multiple files (see the next topic, Choosing Search Options), VLISP displays the matches it found in an output window. Double-click on any highlighted lines in the Find Output window to open the associated LISP file in a VLISP editor window.

Topics in this section

  • Choosing Search Options
  • Repeating an Earlier Search
  • Replacing Text


Choosing Search Options

Searching for Text
Searching for Text
Repeating an Earlier Search
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Searching for Text >
Choosing Search Options

Under the Search heading, indicate the extent of the search you want VLISP to conduct. You can choose one of the following:

Current Selection

Searches only the text highlighted in the editor window.

Current File

Searches through the entire file in the active editor window.

Find in Project

With this option selected, VLISP prompts you to specify the name of the VLISP project you want to search. It will search all the files in this project and display all matches in a new output window. See Finding a String in Project Source Files for more information on this option.

Find in Files

If you select this option, VLISP allows you to specify a Windows directory (folder) to search for the text. Optionally, you can instruct VLISP to search all subdirectories of that directory as well. VLISP will search through all the files and display all matches in a new output window.

When searching for text within the current file, the Direction setting determines where VLISP looks next for the search text. Choose Down to search forward (toward the end of the file) from the cursor position. Choose Up to search backward (toward the beginning of the file) from the cursor position.

The Find dialog box also includes the following options:

Match Whole Word Only

If selected, VLISP will only match complete words. For example, if the search term is ent and VLISP encounters the word enter in the text, VLISP does not consider this a match. However, if the Match Whole Word Only option is not selected, VLISP considers the ent within enter to be a match.

Match Case

If selected, VLISP only matches text set in the same case. In this instance, Ent and ent are not considered a match. If Match Case is not selected, Ent and ent are considered a match.

Mark Instances

If you select this option, the position of the located text will be added to the bookmark ring (see Bookmarking Text). This lets you return quickly to this code position later. Searches that find all occurrences of a string add each position to the bookmark ring.


Repeating an Earlier Search

Choosing Search Options
Searching for Text
Replacing Text
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Searching for Text >
Repeating an Earlier Search

VLISP saves each search string you enter in a pull-down list on the toolbar.

To repeat a search you made earlier, click the pull-down arrow and select a search term from the toolbar list. Press the Find Toolbar String button to conduct the search.


Replacing Text

Repeating an Earlier Search
Searching for Text
Bookmarking Text
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor > Searching for Text >
Replacing Text

The Search menu contains a Replace function that is used to replace the search text with a text string that you specify.

The Replace dialog box is similar to the Find dialog box, but with fewer options. It contains an additional Replace With entry field, in which you specify the text you want VLISP to substitute for the search text. Specify the search text in the Find What field.

You can take the following actions from the Replace dialog box:

  • Press Find Next to find the next occurrence of the search string.
  • Press Replace to replace the found text with the replacement string.

    If you don't want to replace this occurrence of the text, press Find Next to search for the next occurrence of the text, or Cancel to end the search.

  • Press Replace All to replace all occurrences of the search string with the replacement string.
  • Press Cancel to end the Replace function.


Bookmarking Text

Replacing Text
Using the Text Editor
Using Console and Editor Coding Aids
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using the Text Editor >
Bookmarking Text

The bookmark feature helps you navigate through VLISP text editor windows by letting you mark up to 32 positions (bookmarks) in each window. Once 32 bookmarks are set, adding a new bookmark results in the oldest bookmark being removed.

Each text editor window maintains its own set of bookmarks, and the bookmark navigation tools let you walk through the marks within each window independently of the other windows. A set of bookmarks within a window is known as a bookmark ring. You can step either forward or backward through the ring, and eventually return to the starting point.

Whenever you step to a bookmark, VLISP automatically places a marker at the location you are stepping from. In effect, the marker for the place you are jumping to is moved to the place you jumped from. This makes it easy to return to your original location just by stepping back in the opposite direction, or by cycling through all the bookmarks until you get back to the starting point.

To add a bookmark

  1. Move the cursor to the location you want to mark.

  2. Press the Toggle Bookmark button on the toolbar, or press ALT +. (ALT plus a period).

Bookmarks may also be inserted automatically when using the Find command to search for text. See the discussion on search options in Searching for Text for more information on this feature.

To move the cursor from one bookmark to the next

  1. Move the cursor to the previous bookmark in the ring by choosing Search [image] Bookmarks [image] Previous Bookmark, or by pressing the Previous Bookmark toolbar icon. You can also accomplish this by pressing CTRL +, (CTRL plus a comma).

  2. Move the cursor to the next bookmark in the ring by choosing Search [image] Bookmarks [image] Next Bookmark, or by pressing the Next Bookmark toolbar icon. You can also accomplish this by pressing CTRL +. (CTRL plus a period).

In addition to jumping between bookmarks, you can also jump and select the text between two bookmarks.

To move the cursor and select text between bookmarks

  1. Press CTRL + SHIFT +, (comma) to select the text between the current location and the next bookmark.
  2. Press CTRL + SHIFT +. (period) to select the text between the current location and the previous bookmark.

Removing a bookmark is similar to setting a bookmark.

To remove a bookmark

  1. Move the cursor to the bookmarked location.
  2. Press the Toggle Bookmark button, or press ALT +. (ALT plus a period).

    The Toggle Bookmark command works as an on/off switch. If you issue the command when a bookmark is set, Toggle Bookmark turns it off. Issue the same command when there is no bookmark set, and Toggle Bookmark inserts a bookmark.

  3. To remove all the bookmarks in the active window, press the Clear All Bookmarks button on the toolbar, or choose Search [image] Bookmarks [image] Clear All Bookmarks from the VLISP menu.


Using Console and Editor Coding Aids

Bookmarking Text
Developing Programs with Visual LISP
Understanding Visual LISP Color Coding
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP >
Using Console and Editor Coding Aids

Several VLISP coding aids are useful at both the Console and text editor windows. One highly visual aid is the assignment of colors to AutoLISP language elements. Color coding helps you detect syntax errors in your code. VLISP also contains several features to help you determine the names of variables and functions that you need to refer to in your program, and shortcuts to online Help for AutoLISP functions.

Topics in this section

  • Understanding Visual LISP Color Coding
  • Using the Apropos Feature
  • Letting Visual LISP Help You Complete Words
  • Getting Help for AutoLISP Functions


Understanding Visual LISP Color Coding

Using Console and Editor Coding Aids
Using Console and Editor Coding Aids
Using the Apropos Feature
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids >
Understanding Visual LISP Color Coding

As soon as you enter text in the VLISP Console or text editor windows, VLISP attempts to determine if the entered word is a built-in AutoLISP function, a number, a string, or some other language element. VLISP assigns every type of element its own color. This helps you detect missing quotes or misspelled function names. The default color scheme is shown in the following table.

Default color coding scheme for AutoLISP code
AutoLISP language element | Color
Built-in functions and protected symbols | Blue
Strings | Magenta
Integers | Green
Real numbers | Teal
Comments | Magenta, on gray background
Parentheses | Red
Unrecognized items (for example, user variables) | Black

You can change the default colors by choosing Tools [image] Window Attributes [image] Configure Current from the VLISP menu. See Configure Current for more information on setting colors.

The VLISP text editor provides color coding for LISP files, DCL files, SQL files, and C++ language source files (see LISP, FAS, and Other File Types for a list of file types recognized by VLISP). VLISP uses the file name extension to determine a file's type, and then selects the color coding accordingly. You can change the color coding style associated with a file type by choosing Tools [image] Window Attributes [image] Syntax Coloring from the VLISP menu. All text entered in the Console window is treated as AutoLISP code.


Using the Apropos Feature

Understanding Visual LISP Color Coding
Using Console and Editor Coding Aids
Using the Results of an Apropos Search
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids >
Using the Apropos Feature

The Apropos feature is a tool that searches the VLISP symbol table. The symbol table contains every symbol read by the AutoLISP reader. This includes symbols in user programs and symbols that implement the AutoLISP language.

You can define specific search criteria for Apropos to use in searching the symbol table. For example, you can tell Apropos to search for all symbol names that contain a specific character string, and you can further refine that search to return only symbols that identify functions.

To invoke Apropos, choose View [image] Apropos Window from the VLISP menu, or press the Apropos button on the VLISP toolbar. If you select text prior to invoking Apropos, VLISP immediately performs an Apropos search on the selected text. If no text is selected, VLISP displays the Apropos Options dialog box.

In the input field of the Apropos Options dialog box, enter the text you want Apropos to search for. The dialog box contains the following options:

Match by Prefix

If this option is turned on, Apropos searches for a match starting only from the first character of the symbol name. If the option is turned off, Apropos tries to match the text you entered starting at any position of a symbol name.

For example, with Match by Prefix off, a search on the word get returns symbol names including getint, getpoint, ssget, and vla-getActive. With Match by Prefix on, the same search does not return ssget and vla-getActive, because get appears in the middle of those symbol names, not at the beginning.

Use WCMATCH (wild card match)

If this option is turned on, Apropos treats asterisks as wild-card characters when searching. For example, if you specify fun* as the symbol you want matched, Apropos looks for all names that contain fun, no matter what characters follow. In contrast, with Use WCMATCH turned off, the asterisk is treated as a string and Apropos only matches names that precisely contain fun*.

Downcase Symbols

If this option is turned on, any symbols you copy to the Clipboard with the Apropos service are converted to lowercase characters. If you paste the symbol name in another window, it appears in lowercase.

Filter Flags

This option lets you choose symbols with matching flag settings. VLISP displays a list of check boxes that correspond to the symbol flags described in Understanding Symbol Flags. If the flag filter is on, only symbols set with the selected flags are considered.

Filter Value

Opens the Filter Value dialog box, from which you can select additional search criteria. You can choose one of the following:

All No filter.

Null value Only nil-valued symbols are considered for matching.

Nonull value Only symbols that are not nil are considered for matching.

Functions All function types (user-defined, built-in, and so on) are considered for matching.

User function Only user-defined functions (USUBR) are considered.

Built-in function Only built-in or compiled AutoLISP functions (SUBR) are considered for matching.

Exrxsubr Only external function names are matched.

If you specify a filter value or filter flag, the message area of the Apropos options dialog box indicates your selections.

When you've specified the criteria you want Apropos to use in its search, press OK to conduct the search.

To search for AutoLISP symbols that begin with set

  1. Choose View [image] Apropos Window from the VLISP menu.
  2. Enter set in the text input field of the Apropos options dialog box.
  3. Select the Match by Prefix option.
  4. Clear all other options in the Apropos options dialog box.
  5. Press OK to conduct the search.

Topics in this section

  • Using the Results of an Apropos Search


Using the Results of an Apropos Search

Using the Apropos Feature
Using the Apropos Feature
Letting Visual LISP Help You Complete Words
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids > Using the Apropos Feature >
Using the Results of an Apropos Search

Apropos displays the symbols matching your search criteria in the following window:

The bottom of the Apropos Results window contains a message area with information about the results of the search. In the current example, the message indicates the number of symbols Apropos found in its search.

If the Apropos Results window is not large enough to show all the symbols found, the window is displayed as scrollable. If the search returns over a thousand matches, Apropos will not be able to list all the symbols, even in a scrollable window. The message area in the results window warns you when this occurs, as in the following example from a search on the prefix VL:

If your search results in too many symbols for Apropos to display in the Results window, you can use the Copy to Trace/Log feature to view the complete list of symbols in the VLISP Trace window.

To return to the Apropos Options window and refine your search, press the Apropos options button in the Apropos Results window toolbar.

The toolbar also contains the following buttons:

Copy to Trace/log

Copies the results of the Apropos search to the VLISP Trace window. Data in the Trace window can be copied using the Windows Copy command. If Trace logging is active, the contents are also copied to the log file (see Using Visual LISP Data Inspection Tools for information on Trace logging).

Help

Invokes Help for the selected symbol. The symbol name is used as the Help index search value.

You can also use the Apropos Results window's shortcut menu on selected symbols. For example, you can select a symbol from the list and insert it into the VLISP Console or text editor window.

To insert a symbol from the Apropos Results window

  1. Select a symbol from the list.
  2. Right-click to display the shortcut menu, and choose Copy to Clipboard from the list of options.
  3. Click in the VLISP window at the point you want to insert the symbol name.
  4. Right-click and select Paste from the shortcut menu, or press CTRL + V to paste the text.

The other options on the shortcut menu are:

Inspect

Invoke the VLISP Inspect feature for the selected symbol. See Using Inspect Windows for information on using this feature.

Print

Print the symbol name in the Console window. If you select a symbol name displayed in the Console window and press ENTER, VLISP copies the symbol name to the Console prompt.

Symbol

Invoke the VLISP Symbol Service feature for the selected symbol. See Using the Symbol Service Dialog Box for information on using this feature.

Copy

Copy the selected symbol name to the *obj* IDE global variable.

Add to Watch

Add the selected symbol to the Watch window. See Using the Watch Window for information on using this feature.

Help

Invoke online Help for the selected symbol.


Letting Visual LISP Help You Complete Words

Using the Results of an Apropos Search
Using Console and Editor Coding Aids
Completing a Word by Matching
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids >
Letting Visual LISP Help You Complete Words

Two VLISP features, Complete Word by Match and Complete Word by Apropos, allow you to type part of a word and get help in completing the rest.

Topics in this section

  • Completing a Word by Matching
  • Completing a Word by Apropos


Completing a Word by Matching

Letting Visual LISP Help You Complete Words
Letting Visual LISP Help You Complete Words
Completing a Word by Apropos
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids > Letting Visual LISP Help You Complete Words >
Completing a Word by Matching

Using Complete Word by Match, VLISP completes a partially entered word by matching the part you have typed with another word in the same window. For example, suppose the following shows the history of your VLISP Console window:

_$ (setq origin (getpoint "\nOrigin of inyn sign: "))
_$ (setq radius (getdist "\nRadius of inyn sign: " origin))
_$ (setq half-r (/ radius 2))
_$ (setq origin-x (car origin))
_$ (command "_.CIRCLE" origin radius)

In other words, these are the last five commands that you entered from the Console.

To complete a word by matching

  1. Type the following at the Console prompt:
    _$ (c
  2. Press CTRL + SPACEBAR to invoke Complete Word by Match. VLISP finds the last word you entered that began with the letter “c,” and completes the word you started to type:
    _$ (command
  3. If that is not the word you are looking for, press CTRL + SPCAEBAR again. VLISP searches back through the Console history for the previous occurrence of a word beginning with the letter “c”:
    _$ (car

    VLISP will keep searching for matching words each time you press CTRL + SPACEBAR. If you keep pressing CTRL + SPACEBAR after VLISP finds the last matching word, VLISP repeats the retrieval sequence. (Note that you can also choose Search [image] Complete Word by Match from the VLISP menu instead of pressing CTRL + SPACEBAR to invoke the Match feature.)

    If VLISP does not find any matching words, it does nothing.

    You can use Complete Word by Match in either the Console window or the text editor window. When you invoke the feature from the Console window, VLISP only searches the Console for a match; when invoked from a text editor window, VLISP only searches that editor window for a match.

    The Complete Word by Match feature is not case-sensitive. In the previous example, you would have achieved the same result had you entered a capital C instead of a lowercase c.


Completing a Word by Apropos

Completing a Word by Matching
Letting Visual LISP Help You Complete Words
Getting Help for AutoLISP Functions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids > Letting Visual LISP Help You Complete Words >
Completing a Word by Apropos

With the Complete Word by Apropos feature, VLISP completes a partially entered word with a matching symbol name from the VLISP symbol table. To demonstrate this feature, assume you have entered the following commands shown in your VLISP Console window:

_$ (setq origin (getpoint "\nOrigin of inyn sign: "))
_$ (setq radius (getdist "\nRadius of inyn sign: " origin))
_$ (setq half-r (/ radius 2))
_$ (setq origin-x (car origin))
_$ (command "_.CIRCLE" origin radius)

To use the Complete Word by Apropos feature

  1. At the Console prompt, type the following:
    _$ (ha
  2. Press CTRL + SHIFT + SPACE to invoke Complete Word by Apropos on the partially entered word. VLISP lists all symbol table entries that begin with “ha”:

    VLISP found two matching words in the symbol table. The half-r symbol is a variable you defined in the Console window, and the handent symbol represents an AutoLISP function.

  3. Select the symbol you want to complete your typing. If you do not want to select a symbol, press ESC.

    Note that you can also choose Search [image] Complete Word by Apropos from the VLISP menu instead of pressing CTRL + SHIFT + SPACE to invoke the feature.

    If no symbols match the text you've entered, VLISP displays the Apropos options dialog box:

    The message area of the Apropos options dialog box shows the value that Apropos could not match. See Using the Apropos Feature for information on setting Apropos options and renewing your search.

    If VLISP finds more than 15 matching names in the symbol table, it displays the Apropos Results dialog box. For example, type get at the Console prompt, then press CTRL + SHIFT + SPACEBAR to invoke the Apropos feature. VLISP displays the following dialog box:

    You can select a symbol from the results window and copy it into your code using a shortcut menu. If you need additional help with copying the symbol to your program code, or using other features of the Apropos Results window, see Using the Results of an Apropos Search.


Getting Help for AutoLISP Functions

Completing a Word by Apropos
Using Console and Editor Coding Aids
Formatting Code with Visual LISP
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Using Console and Editor Coding Aids >
Getting Help for AutoLISP Functions

If you select a function name anywhere in a text editor or Console window, and then press the Help button on the Tools toolbar, VLISP displays help for the function. This feature works for any function recognized by VLISP. You can also press CTRL + F1 to view Help for the selected function.


Formatting Code with Visual LISP

Getting Help for AutoLISP Functions
Developing Programs with Visual LISP
Understanding Visual LISP Formatting Styles
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP >
Formatting Code with Visual LISP

The VLISP code formatter arranges the text of AutoLISP expressions in a style that improves text appearance and readability. The code formatter includes a Smart Indent feature to arrange the indentation of program code automatically. The code formatter works automatically as you enter code in a VLISP text editor window. You can also explicitly invoke the formatter to rearrange selected blocks of text or all text in a VLISP editor window. This is useful for formatting text you copy from other editors, or for reformatting your code in a different style.

To format text in an active editor window

  1. To format all the code in the window, choose Tools [image] Format code in Editor from the VLISP menu, or click the Format Edit window button on the Tools toolbar.

  2. To format only part of the code in the editor window, select a fragment of code text and choose Format Code In Selection from the Tools menu, or click the Format Selection button on the Tools toolbar.

If you select text to be formatted, the selection must contain valid AutoLISP expressions or the formatter will issue an error message.

If the formatter finds unbalanced parentheses in your code, an alert box is displayed. Choose Yes to have VLISP add parentheses where it thinks they belong; choose No if you want to fix the parentheses on your own.

NoteThe VLISP formatter can balance the number of parentheses but usually does not insert the additional parentheses in the right places. See Checking the Balance of Parentheses for more information on detecting and correcting unmatched parentheses.

The VLISP Smart Indent feature works in the background as you type in the text editor. The indent is evaluated up to the current AutoLISP parenthesis nesting level. If the current expression is preceded by only a sequence of completed top-level AutoLISP expressions, the indentation will be zero. You can affect the amount of indentation by specifying Visual LISP format options; see the next two topics.

Topics in this section

  • Understanding Visual LISP Formatting Styles
  • Applying Formatting Options
  • Applying Visual LISP Comment Styles
  • Saving and Restoring Formatting Options
  • Formatter Restrictions
  • Formatting Shortcut Keys


Understanding Visual LISP Formatting Styles

Formatting Code with Visual LISP
Formatting Code with Visual LISP
Plane Style
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP >
Understanding Visual LISP Formatting Styles

The VLISP formatter chooses the appropriate formatting style according to rules that are explained in this section. You can influence the choice of VLISP styles through the options you set in the Format Options dialog box. To display the Format Options dialog box, choose Tools [image] Environment Options [image] Visual LISP Format Options from the VLISP menu.

Initially, VLISP displays only a subset of the formatting options you can specify. Press the More Options button in the Format Options dialog box to expand the window with additional formatting options.

The following are two main formatting style sets:

  • A single-line formatting style—Plane
  • Multiple-line formatting styles—Wide, Narrow, Column

The sample text below demonstrates the different formatting styles.

Sample text initial appearance:

(autoload "appload"
'("appload"))

For a general function call expression, the formatter applies one of the styles in the following sections.

Topics in this section

  • Plane Style
  • Wide Style
  • Narrow Style
  • Column Style


Plane Style

Understanding Visual LISP Formatting Styles
Understanding Visual LISP Formatting Styles
Wide Style
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Understanding Visual LISP Formatting Styles >
Plane Style

In the Plane style, all arguments are placed in the same line, separated by a single space:

(autoload "appload" '("appload"))

The Plane style is applied to an expression when all the following conditions are met:

  • The expression's last character position does not exceed the value of the Right Text Margin environment option.
  • The expression's printing length is less than the value of the Approximate Line Length environment option (that is, last character position minus starting indentation position is less than this value).
  • The expression does not contain embedded comments with Newline characters.


Wide Style

Plane Style
Understanding Visual LISP Formatting Styles
Narrow Style
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Understanding Visual LISP Formatting Styles >
Wide Style

In the Wide style, the first argument is placed in the same line as the function name, and other arguments are aligned in a column below the first argument.

(autoload "appload"
          '("appload")
                  )

The Wide style applies to an expression when the following conditions are met:

  • The Plane style cannot be applied.
  • The first element is a symbol, and the first element's length is less than the Maximum Wide Style Car Length environment option.


Narrow Style

Wide Style
Understanding Visual LISP Formatting Styles
Column Style
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Understanding Visual LISP Formatting Styles >
Narrow Style

In the Narrow style, the first argument is placed on the next line after the function name, and other arguments are aligned in a column below the first argument. The displacement of the first argument's starting position relative to the expression starting position is controlled by the value of the Narrow Style Indentation environment option (in the following example, this value is equal to 2):

(autoload
  "appload"
  '("appload")
)

The Narrow formatting style applies for progn expressions, and for those instances when the Plane and Wide formatting styles cannot be applied.


Column Style

Narrow Style
Understanding Visual LISP Formatting Styles
Applying Formatting Options
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Understanding Visual LISP Formatting Styles >
Column Style

In the Column style, all elements are positioned in a column. This style is appropriate for displaying quoted lists and COND-expression clauses. For example, the following text:

'((10 "{insertion}")      (1 "{string}")
(7 "{style}"))

would be displayed as:

'((10 "{insertion}")
  (1 "{string}")
  (7 "{style}")
)


Applying Formatting Options

Column Style
Formatting Code with Visual LISP
Close Parenthesis Style
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP >
Applying Formatting Options

In addition to affecting the basic formatting styles, you can choose from a number of Visual LISP format options.

Topics in this section

  • Close Parenthesis Style
  • Insert Form-Closing Comment
  • Preserve Existing Line Breaks
  • Split Comments
  • Long List Format Style
  • Setting Case for Symbols


Close Parenthesis Style

Applying Formatting Options
Applying Formatting Options
Insert Form-Closing Comment
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Applying Formatting Options >
Close Parenthesis Style

This style controls the position of the close parenthesis for multiple-line formatting styles. You can select one of the following options:

Close at the Same Line

Close parenthesis on the last line of each formatting expression.

Close at the New Line with Inner Indentation

Close parenthesis on the next line following the last line of each formatting expression with the inner indent.

Close at the New Line with Outer Indentation

Close parenthesis on the next line following the last line of each formatting expression with the outer indent.

Examples

The initial expression is written as:

(cond
 ((/= (logand mask flg) 0)
 (list (list txton)))
)

Formatting result when Close at the Same Line option is selected:

(cond ((/= (logand mask flg) 0)
       (list (list txton))))

Formatting result when Close at the New Line with Inner Indentation option is selected:

(cond ((/= (logand mask flg) 0)
       (list (list txton))
       )
      )

Formatting result when Close at the New Line with Outer Indentation is selected:

(cond ((/= (logand mask flg) 0)
       (list (list txton))
      )
)


Insert Form-Closing Comment

Close Parenthesis Style
Applying Formatting Options
Preserve Existing Line Breaks
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Applying Formatting Options >
Insert Form-Closing Comment

If you select this option, VLISP adds a comment following the close of an expression. However, the option takes effect only if the Close Parenthesis Style format setting is either Close at the New Line with Inner Indentation or Close at the New Line with Outer Indentation.

When the Insert Form-Closing Comment option is on, the VLISP formatter inserts a comment of the form

;_ end of <function name>

after each multiple-line function. This comment does not appear if an inline-comment, single-semicolon comment, or pasted-comment exists after the function call. You can change the comment text by entering a different comment in the Form-Closing Comment prefix field of the Format Options dialog box.

Example

Initial text:

(autoarxload "image"
           '("gifin" "pcxin" "riaspect" "ribackg" "riedge"
"rigamut" "rigrey"  "rithresh" "tiffin"))

Formatted text:

(autoarxload "image"
         '("gifin"      "pcxin"      "riaspect"
           "ribackg"    "riedge"     "rigamut"
          "rigrey"     "rithresh"   "tiffin"
          )
) ;_ end of autoarxload

Note the _ end of autoarxload comment in the last line of code.


Preserve Existing Line Breaks

Insert Form-Closing Comment
Applying Formatting Options
Split Comments
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Applying Formatting Options >
Preserve Existing Line Breaks

When the Preserve Existing Line Breaks option is on, the VLISP formatter inserts new lines whenever a new line is detected in the text it is formatting. When the option is off, the formatter can squeeze a multiple-line expression to the Plane style, if it fits within the right margin.

The following example shows how the Preserve Existing Line Breaks option works.

Initial text:

(if (/= s "Function canceled")   (princ (strcat
    "\nError: "
      s)) ;single semicolon cmt
)

Formatting result if the option is on (default):

(if (/= s "Function canceled")
  (princ (strcat
           "\nError: "
           s
         )
  )                                ;single semicolon cmt
)

Formatting result when the option is off:

(if (/= s "Function canceled")
  (princ (strcat "\nError: " s))    ;single semicolon cmt
)

Note that multiple-line princ and strcat expressions are compressed to a single line.


Split Comments

Preserve Existing Line Breaks
Applying Formatting Options
Long List Format Style
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Applying Formatting Options >
Split Comments

When the Split Comments option is on, the formatter splits long comments that extend past the right margin.

For the previous example, if the Right Text Margin setting is 60, and Single-Semicolon comment indentation is 40, the formatter will split the comment as follows:

(if (/= s "Function canceled")
(princ (strcat "\nError: " s))    ;single
                                  ;semicolon cmt
)


Long List Format Style

Split Comments
Applying Formatting Options
Setting Case for Symbols
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Applying Formatting Options >
Long List Format Style

Long lists are lists of formal arguments in defun, lambda, or quoted lists containing more than five elements. The Long List format style applies to lists that do not fit on a single line (within the Right Text Margin).

If the Long List format style options do not appear in your Format Options dialog box, press the More Options button to display additional formatting options. The available modes for Long List format are listed below and illustrated with an example based on the following list elements, and with Right Text Margin set to 45:

'("entdel" "entmake" "entmod" "entnext"
"entsel" "entupd")

Single-Column formatting:

      '("entdel"
        "entmake"
        "entmod"
        "entnext"
        "entsel"
        "entupd"
       )

Two-Column formatting:

      '("entdel"      "entmake"
        "entmod"      "entsel"
        "entnext"     "entupd"
       )

Multi-Column formatting:

      '("entdel"     "entmake"     "entmod"
        "entsel"     "entnext"     "entupd"
       )

Fill-the-String formatting (places as many quoted strings on one line as possible, up to the right margin):

  '("entdel" "entmake" "entmod" "entsel" "entnext" "entupd"
   )

The Preserve Existing Line Breaks option, if selected, may supersede the formatting indicated by Long List format style.


Setting Case for Symbols

Long List Format Style
Applying Formatting Options
Applying Visual LISP Comment Styles
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP > Applying Formatting Options >
Setting Case for Symbols

By default, the VLISP formatter does not change the case of AutoLISP symbols. You can set the formatter to change the case of symbols according to the VLISP protection state for symbols.

The Protected options subgroup controls the case conversion of protected symbols (built-in symbols or symbols with the ASSIGN-PROTECT flag set). The Unprotected options subgroup controls case conversion of unprotected (user) AutoLISP symbols.

Case settings for symbols
Setting | Effect
None | Does not change the case
downcase | Forces all characters in a symbol's name to lowercase
UPCASE | Forces all characters in a symbol's name to uppercase


Applying Visual LISP Comment Styles

Setting Case for Symbols
Formatting Code with Visual LISP
Saving and Restoring Formatting Options
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP >
Applying Visual LISP Comment Styles

The VLISP formatter recognizes five types of AutoLISP comments, and positions each comment according to its type.

Visual LISP comment formatting
Comment | Formatted appearance
;| Inline |; | The single-line comment appears after formatting as any other expression; the multiple-line comment appears starting at a new line
; Single-Semicolon | Starts at the comment-column position, as defined by the “Single-Semicolon comment indentation” format option
;; Current-Column | The comment appears starting on a new line, indented at the same level as the last line of program code
;;; Heading or 0-Column | Appears on a new line, without indentation
;_ Function-Closing | Appears just after the previous expression

The following example demonstrates each comment style.

Initial text:

 (defun foo (x)
    ;|inline comment |;
     (list 1 2 3) ;comment-column comment
   ;;current-column comment
   ;;; heading or 0-column comment
   )      ;_ function-closing comment

Formatted text:

(defun foo (x) ;|inline comment |;
   (list 1 2 3)                       ;comment-column comment
   ;;current-column comment
;;; heading or 0-column comment
   ) ;_ function-closing comment


Saving and Restoring Formatting Options

Applying Visual LISP Comment Styles
Formatting Code with Visual LISP
Formatter Restrictions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP >
Saving and Restoring Formatting Options

To save your formatting options so that they carry over to subsequent VLISP sessions, choose Tools [image] Save Settings from the VLISP menu. Alternatively, you can save the current settings specifically for the program in the active text editor window. VLISP saves formatter settings in a program when the Save Formatting Options in Source File option is selected. To select or cancel this option, choose Environment Options [image] Visual LISP Format Options from the Tools menu. If the option is in effect, VLISP adds formatting information as comments at the end of the program, when you run the formatter.

Each formatter invocation checks for formatting options settings at the bottom of the selected text. If found, these settings override the session settings listed in Tools [image] Environment Options [image] Visual LISP Format Options.


Formatter Restrictions

Saving and Restoring Formatting Options
Formatting Code with Visual LISP
Formatting Shortcut Keys
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP >
Formatter Restrictions

The following restrictions apply to the VLISP code formatter:

  • The formatter relies on a fixed window font and a particular tab size. To change font settings, choose Window Attributes [image] Font; to change tab settings, choose Window Attributes [image] Configure Current.
  • The formatter is available only within VLISP text editor windows.
  • Existing SPACE and TAB characters placed outside of inline comments and strings will not influence the formatting result.


Formatting Shortcut Keys

Formatter Restrictions
Formatting Code with Visual LISP
Checking for Syntax Errors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Formatting Code with Visual LISP >
Formatting Shortcut Keys

Press CTRL + E while in an active VLISP text editor window to display a list containing the following editor options.

Text editor code formatting commands
Option | Effect
Indent Block | Indents the selected block of text by adding a tab to the beginning of each line
Unindent | Unindents the selected block of text by removing a tab
Indent to Current Level | Indents the current line to the same level as the previous line of program code
Prefix With | Adds a text string to the beginning of the current line, or to each line in a block of selected lines, after prompting you for the string
Append With | Appends a text string to selected lines of text, after prompting you for the string
Comment Block | Converts a block of code to comments
Uncomment Block | Changes a block of comments to active text
Save Block As | Copies selected text to a new file
Upcase | Converts the selected text to all uppercase
Downcase | Converts the selected text to all lowercase
Capitalize | Capitalizes the first letter of each word in the selected text
Insert date | Inserts the current date (default format is MM/DD/YY)
Insert time | Inserts the current time (default format is HH:MM:SS)
Format Date/Time | Changes the date and time format
Sort Block | Sorts the selected block of code in alphabetical order
Insert File | Inserts the contents of a text file into the current editor window at the cursor position
Delete to EOL | Erases everything from the cursor position to the end of the current line
Delete Blanks | Deletes all blank spaces from the cursor position to the first non-blank character in the line


Checking for Syntax Errors

Formatting Shortcut Keys
Developing Programs with Visual LISP
Checking the Balance of Parentheses
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP >
Checking for Syntax Errors

One main attraction of using VLISP is the extensive debugging tools it provides. These tools allow you to watch what your program is doing while it is executing, and to take a “snapshot” of your program at any point. However, VLISP also provides a number of features designed to detect program errors before you run the program.

Topics in this section

  • Checking the Balance of Parentheses
  • Using Color Coding to Detect Syntax Errors
  • Using the Check Command to Look for Syntax Errors


Checking the Balance of Parentheses

Checking for Syntax Errors
Checking for Syntax Errors
Using Color Coding to Detect Syntax Errors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Checking for Syntax Errors >
Checking the Balance of Parentheses

AutoLISP uses parentheses more frequently than most other computer languages. One of the most frequent syntax errors in AutoLISP is an unequal number of open and close parentheses. VLISP includes a number of tools to help you detect unbalanced or unmatched parentheses.

As noted in To format text in an active editor window, the VLISP code formatter searches for unbalanced parentheses when it formats your code. If you allow it to, the formatter will add parentheses where it thinks they are missing. Typically, though, the VLISP formatter adds parentheses at the end of a program, not to where you really need them. If you let VLISP add the parentheses, you will probably have to remove them later.

NoteIf you do not allow the formatter to add the balancing parentheses, it won't format your code either.

In any event, you must check the structure of your program to determine where the parentheses are really missing. You can use these parentheses matching items from the Edit menu to help you find unbalanced parentheses:

Match Forward (CTRL +])

Moves the insertion point (marked by the cursor) just past the close parenthesis that matches an open parenthesis.

If the current cursor position is just before an open parenthesis, VLISP matches that parenthesis with its closing parenthesis. If the cursor position is in the middle of an expression, VLISP matches the current expression's open parenthesis with its closing parenthesis.

Match Backward (CTRL +[)

Moves the insertion point to just before the open parenthesis that matches a close parenthesis.

If the current cursor position is just after a close parenthesis, VLISP matches that parenthesis with its opening parenthesis. If the cursor position is in the middle of an expression, VLISP matches the current expression's close parenthesis with its open parenthesis.

Select Forward (CTRL + SHIFT +]

Moves the insertion point as the Match Forward command does, but also selects all text between the start and end positions.

With the cursor positioned right before an open parenthesis, double-clicking also selects all text up to the matching close parenthesis, but does not move the insertion point.

Select Backward (CTRL + SHIFT +[)

Moves the insertion point as the Match Backward command does, but also selects all text between the start and end positions.

With the cursor positioned right after a close parenthesis, double-clicking also selects all text up to the matching open parenthesis, but does not move the insertion point.

For example, look at the following code:

1 (defun yinyang (/ origin radius i-radius half-r origin-x origin-y)
2 (setq half-r (/ radius 2))
3 (setq origin-x (car origin))
4 (setq origin-y (cadr origin))
5 (command "_.CIRCLE"
6          origin
7          radius
8          (command "_.ARC"
9                "_C"
10                (list origin-x (+ origin-y half-r))
11                (list origin-x (+ origin-y radius))
12                 origin
13         )
14         (command "_.ARC"
15                "_C"
16               (list origin-x (- origin-y half-r))
17                (list origin-x (- origin-y radius))
18                origin
19         )
20 )

(The line numbers are not part of the text; they are used to help explain the example.)

Here is what happens if you load this code in VLISP and continually issue the Match Forward command, starting with the insertion point at the beginning of line 1.

  • VLISP does not find a matching close parenthesis, so the cursor does not move.
  • Move the cursor to the beginning of line 2.
  • Cursor moves to the end of line 2.
  • Cursor moves to the end of line 3.
  • Cursor moves to the end of line 4.
  • Cursor jumps to the last right parenthesis in the program. (20)

In other words, the close parenthesis that matches the open parenthesis on line 5 is the last parenthesis in the program. You know this is an error because the last close parenthesis in an AutoLISP program should match the open parenthesis of the program's defun. Notice also that all the statements after line 5 are indented in a manner unlike in the preceding program code. These two clues indicate something is amiss at this point in the program. In fact, the close parenthesis to the command that begins on line 5 is missing.


Using Color Coding to Detect Syntax Errors

Checking the Balance of Parentheses
Checking for Syntax Errors
Using the Check Command to Look for Syntax Errors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Checking for Syntax Errors >
Using Color Coding to Detect Syntax Errors

The AutoCAD Sample\VisualLISP directory contains a file named drawline-with-errors.lsp. It is similar to the drawline.lsp program file introduced earlier in this manual, but it contains a couple of errors. Open the file in VLISP, so that you can see how color is used in the file:

(defun drawline(/ pt1 pt2) ; Local variables declared
  ;; get two points from the user
  (setq pt1 (getpoint "\nEnter the start point for the line: "))
(setq pt2 (getpoint pt1 "\nEnter the end point for the line: "))
  ;; check to see that the two points exist
  (iff (and pt1 pt2)
       (command "_.line" pt1 pt2 "")
       (princ "\nInvalid or missing points!")
       (princ)      ;;  exit quietly
  )
)

If you use the standard VLISP syntactic colorations, systems functions such as setq, defun, getdist, getpoint, and / are displayed in blue. The items VLISP does not recognize, such as user-defined variables, are printed in black. In this example, if you look at the unrecognized elements in the program, the word iff might easily catch your eye. Change it to the correct spelling, if, and the color immediately changes to blue.


Using the Check Command to Look for Syntax Errors

Using Color Coding to Detect Syntax Errors
Checking for Syntax Errors
Finding the Location of the Syntax Error in Your Program
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Checking for Syntax Errors >
Using the Check Command to Look for Syntax Errors

You can perform additional syntax checking with the VLISP Check command. The Check command can detect the following errors:

  • Incorrect number of arguments supplied to a known function
  • Invalid variable name passed to a function (for example, a quoted symbol where a variable is required)
  • Incorrect syntax in special form function calls (for example, lambda, setq, and foreach)

Some syntax errors can only be determined at runtime and Check cannot detect these errors. For example, if you call a function that expects an integer argument and you supply a string, AutoLISP does not detect this until run-time. As a result, this error will not be detected until you run your program.

To run the Check command on text in an editor window

  1. Switch to the editor window containing the code you want to check.
  2. To check the entire file, choose Tools [image] Check Text in Editor from the VLISP menu.

  3. To check the syntax of a selected piece of code instead of the whole program, choose Tools [image] Check Selection.

VLISP displays error messages in a new Build Output window, if it detects errors. For example, if you change the iff in drawline-with-errors.lsp to if and run Check, the following error message results:

The message indicates that an if function call contains too many arguments.

Topics in this section

  • Finding the Location of the Syntax Error in Your Program


Finding the Location of the Syntax Error in Your Program

Using the Check Command to Look for Syntax Errors
Using the Check Command to Look for Syntax Errors
Debugging Programs
AutoLISP Developer's Guide > Using the Visual LISP Environment > Developing Programs with Visual LISP > Checking for Syntax Errors > Using the Check Command to Look for Syntax Errors >
Finding the Location of the Syntax Error in Your Program

If you double-click on the error message in the Build Output window, VLISP activates the editor window, places the cursor at the beginning of the statement that caused the error, and highlights the entire expression, as follows:

This error results from the last princ statement following the if. The if statement only allows two arguments: the statement to execute if the expression is true, and the statement to execute if the expression is false. The last princ statement, which is used in this program to cause a quiet exit, belongs after the close parenthesis that currently follows it. (See Exiting Quietly for an explanation of a quiet exit.) If you move the statement to the correct location and run Check again, the code should pass as error-free.


Debugging Programs

Finding the Location of the Syntax Error in Your Program
Using the Visual LISP Environment
Introducing Visual LISP Debugging Features
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Debugging Programs

To debug a program, you can trace execution, trace the values of variables during execution, and view the sequence in which expressions are evaluated.

Programs do not always behave in the way they were intended. When the results you get appear to be wrong, or cause the program to fail, it can be difficult to determine what is going wrong. Visual LISP® provides many features that help you with the debugging process—finding and resolving program problems.

Topics in this section

  • Introducing Visual LISP Debugging Features
  • Learning by Example
  • Using the Visual LISP Debugging Features
  • Using Visual LISP Data Inspection Tools


Introducing Visual LISP Debugging Features

Debugging Programs
Debugging Programs
Learning by Example
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs >
Introducing Visual LISP Debugging Features

Debugging is usually the most time-consuming stage in the development of any program. For this reason, VLISP includes a powerful debugger that provides the following features:

  • Tracing of program execution
  • Tracing of variable values during program execution
  • Viewing the sequence in which various expressions are evaluated
  • Inspecting the values of parameters used within function calls
  • Interrupting program execution
  • Stepping through program execution one instruction at a time
  • Inspecting the stack

VLISP provides the following facilities to implement these features:

Break Loop Mode

Halts program execution at specified points, allowing you to look at and modify the value of objects during the break. Examples of AutoLISP® objects are variables, symbols, functions, and expressions.

Inspect

Provides detailed information on an object in an Inspect dialog box. If the object being inspected is composed of nested objects (a list, for example), the Inspect feature allows you to inspect all the components, each one listed on its own line within the window. You can also recursively inspect any nested object until an atomic object (such as a number or a symbol) is reached.

Watch Window

Watches the values of variables during program execution. The content of the Watch window is updated automatically. This means that if the value of a variable placed in the Watch window is changed, this change will automatically be reflected in the Watch window.

Trace Stack Facility

Views the function call stack. The call stack is a mechanism by which VLISP records the sequence of functions as they are executed by your program. You can view the stack during a debugging session (when the program is in a suspended state, such as stepping through after a breakpoint), or after your program has crashed. If viewed after your program crashes, the function call stack shows what VLISP was doing at the moment the application failed.

Trace Facility

A standard LISP facility, logs the calls and returns values of traced functions into the special Trace window.


Learning by Example

Introducing Visual LISP Debugging Features
Debugging Programs
Stepping through the Debugging Example
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs >
Learning by Example

This section takes you through a VLISP sample program and demonstrates some VLISP debugging facilities along the way. You can find the sample program, yinyang.lsp, in the Sample\VisualLISP directory under the default AutoCAD installation path. Open the file in VLISP so that you can try the examples in this section.

Topics in this section

  • Stepping through the Debugging Example


Stepping through the Debugging Example

Learning by Example
Learning by Example
Setting a Breakpoint to Interrupt Program Execution
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example >
Stepping through the Debugging Example

First, load the yinyang.lsp file and run the yinyang function to see what it does. The function draws the yin-yang symbol, which is used in many religions:

When you run the program, VLISP passes control to AutoCAD and you need to respond to the prompts in the AutoCAD Command window.

VLISP evaluates AutoLISP programs by evaluating the expressions contained in parentheses. These parenthetical expressions are similar to operators in other programming languages such as C++ and Visual Basic 6. The VLISP debugger uses an expression-based approach, unlike the line-by-line debuggers of languages such as C. In the expression-based approach, the debugger can suspend program execution immediately before or after the evaluation of any expression.

Debugging options are controlled from several different places within VLISP, including the text editor, the System Console, and various menus.

Topics in this section

  • Setting a Breakpoint to Interrupt Program Execution
  • Stepping through the Program
  • Monitoring the Evaluation Results of an Expression
  • Continuing Program Execution
  • Running in Animate Mode


Setting a Breakpoint to Interrupt Program Execution

Stepping through the Debugging Example
Stepping through the Debugging Example
Stepping through the Program
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example > Stepping through the Debugging Example >
Setting a Breakpoint to Interrupt Program Execution

Begin by entering some debugging information in the text editor window containing the yinyang.lsp program.

To set a breakpoint that interrupts program execution

  1. Move the cursor in front of the open parenthesis in the line of code that reads:
    (setq half-r (/ radius 2))

    The following screen snapshot indicates the position of this statement within the program:

  2. Click the Toggle Breakpoint button in the Debug toolbar, or choose Debug [image] Toggle Breakpoint from the VLISP menu. Toggle Breakpoint switches breakpoints on and off. When no breakpoint exists, Toggle Breakpoint adds a break; if a breakpoint already exists at the cursor position, Toggle Breakpoint removes it.

  3. Load the yinyang function, if you have not done so already, run it from the VLISP Console prompt by entering the following command:
    (yinyang)

    After you reply to the prompts the program displays at the AutoCAD command line, VLISP halts yinyang execution at the breakpoint you set and displays the code in the text editor window:

    Note how the statement following the cursor is highlighted.


Stepping through the Program

Setting a Breakpoint to Interrupt Program Execution
Stepping through the Debugging Example
Monitoring the Evaluation Results of an Expression
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example > Stepping through the Debugging Example >
Stepping through the Program

The Step commands allow you to move through a program by executing one or more expressions at a time.

To step through a program from a breakpoint

  1. Click the Step Into button, or choose Debug [image] Step Into from the VLISP menu. You can also press F8 to issue the Step Into command.

    Execution begins and halts before evaluation of the inner parenthetical expression, that is, before the specified division occurs. The expression is highlighted, as shown in the following figure:

    Now look at the Step Indicator button on the Debug toolbar; it is the last button on that toolbar.

    The Step Indicator button is active when you are stepping through a program. It indicates where you are in relation to the expression at the breakpoint. The current symbol indicates that you are stopped just before an open parenthesis.

  2. Click the Step Into button again. The cursor moves to a position directly after the evaluated expression, and the Step Indicator button indicates this.
  3. Click the Step Into button again. The cursor moves to the end of the entire statement (the expression and all nested expressions).
  4. Click the Step Into button again and the cursor moves to a position just before the beginning of the statement on the next line:

  5. Now take a bigger step. Click the Step Over button, or choose Debug [image] Step Over from the menu, or press SHIFT + F8 to issue this command:

With the Step Over command, VLISP evaluates an entire expression (and all nested expressions), then stops at the end of the overall expression. The cursor moves to the end of the evaluated expression.


Monitoring the Evaluation Results of an Expression

Stepping through the Program
Stepping through the Debugging Example
Continuing Program Execution
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example > Stepping through the Debugging Example >
Monitoring the Evaluation Results of an Expression

As you step through a program, you may want to monitor the values resulting from the evaluation of individual expressions.

To monitor variables during program execution

  1. From the Debug menu, choose Watch Last Evaluation.

    VLISP displays the Watch window, which shows the value of the *LAST-VALUE* IDE global variable. VLISP always stores the value of the last evaluated expression in the *LAST-VALUE* variable.

  2. In the text editor window containing yinyang.lsp, double-click on any occurrence of the variable name origin-y.
  3. Click the Add Watch button in the Watch window. VLISP passes the origin-y variable name to the Watch window and displays the current value of the variable in the window:

    If the Watch window is not already open and you want to view a variable's value, you can open the window by choosing View [image] Watch Window from the VLISP menu.

    If you click the Watch window's Add Watch button without double-clicking on a variable name first, the following window appears:

    In this window, you can enter the name of the variable you want to view. VLISP may anticipate your choice by copying the name of the variable nearest the cursor into the window. If this is not the one you want to view, simply type over the name.

    VLISP updates the variables in the Watch window after each execution step.

  4. Click the Step Over button (or press SHIFT + F8) twice.

    In the Watch window, note how the value of origin-y changes. It was nil at first, but after execution it took on the value corresponding to the point you clicked in the AutoCAD window.


Continuing Program Execution

Monitoring the Evaluation Results of an Expression
Stepping through the Debugging Example
Running in Animate Mode
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example > Stepping through the Debugging Example >
Continuing Program Execution

To continue running your program to the next breakpoint, or to the end, if there are no more breakpoints, press the Continue button on the Debug toolbar, or choose Debug [image] Continue from the VLISP menu.


Running in Animate Mode

Continuing Program Execution
Stepping through the Debugging Example
Using the Visual LISP Debugging Features
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example > Stepping through the Debugging Example >
Running in Animate Mode

Another debugging feature, animation, allows you to watch as VLISP steps through your program code and evaluates each expression. In Animate mode, it's as if VLISP repeatedly enters a Step Into command for you. Text editor windows highlight expressions being evaluated, and the Watch window continuously updates its data.

To see how Animate mode works

  1. Turn on Animate mode by choosing Debug [image] Animate from the VLISP menu.
  2. Enter (yinyang) at the Console prompt to begin executing the program.

    You'll see each function highlighted as VLISP evaluates the function. You'll be prompted for input, as usual. Notice how the Watch window is updated whenever a watched variable changes. Because you previously set a breakpoint in the program, execution will halt at that breakpoint.

  3. After you stop at the breakpoint, press the Continue button to resume execution; VLISP resumes executing in Animate mode.

You can also interrupt animation by pressing BREAK (it's the key next to SCROLL-LOCK on most keyboards). Once animation is paused you can add Watch values, set variables to new values, and add breakpoints.

To adjust the rate of animation, choose Tools [image] Environment Options [image] General Options, and select the Diagnostic tab. The Animation Delay setting defines the pause between program steps, in milliseconds.

To turn off Animate mode, choose Debug [image] Animate from the VLISP menu again.


Using the Visual LISP Debugging Features

Running in Animate Mode
Debugging Programs
Starting a Debugging Session
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs >
Using the Visual LISP Debugging Features

In addition to setting breakpoints and running in Animate mode, as described in the Learning by Example section of this chapter, VLISP provides a number of other options for controlling program execution.

Stop Once

Causes VLISP to break unconditionally when it evaluates the very first LISP expression encountered. You turn on this mode of operation by choosing Debug [image] Break on Error from the VLISP menu.

Break on Error

Automatically activates the interactive break loop whenever your program encounters a runtime error. You turn on this mode of operation by choosing Debug [image] Stop Once from the VLISP menu.

Note that if this option is selected, some errors that result from function calls entered at the AutoCAD Command prompt will cause VLISP to get focus. That is, the active window may switch from AutoCAD to the VLISP Console window, where you will be in a break loop.

Break on Function Entry

Sets the Debug-on-Entry flag for a function's name symbol, causing a break to occur every time you invoke that function. At the break, the source code for the function will be shown in a special window. You can set or clear the Debug-on-Entry flag interactively with the Symbol Service dialog box. See Using the Symbol Service Dialog Box for information on setting this flag.

Top-Level Debugging Mode

Controls the loading of a program from a file or an editor window. If the option is set, breaks occur before evaluating every top-level expression (such as defun). The Top-Level debugging mode is turned on by switching off the Do Not Debug Top Level option. To find the check box for this option, choose Tools [image] Environment Options [image] General Options from the VLISP menu, then click the Diagnostic tab.

If Top-Level debugging and Stop Once mode are turned on, VLISP will enter the debugging mode every time you load a file because VLISP is debugging defun, setq, and other functions defined within the file as they are loaded. This is usually not a helpful debugging technique and should only be required in rare instances.

Topics in this section

  • Starting a Debugging Session
  • Understanding Break Loops
  • Using Breakpoints


Starting a Debugging Session

Using the Visual LISP Debugging Features
Using the Visual LISP Debugging Features
Understanding Break Loops
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features >
Starting a Debugging Session

The easiest way to start debugging is to choose Debug [image] Stop Once from the VLISP menu. When this item is selected, the evaluation of the first LISP expression will be interrupted. After that you can resume program execution using various Debugger commands. Another way to enter into the debugger mode is to set a breakpoint, as shown in Setting a Breakpoint to Interrupt Program Execution.

When a break occurs, the corresponding VLISP text editor window will show the current LISP expression at the point which the break took place. A break loop marker will appear in the Console window. Using the Console window, you can access and manipulate the program environment in which the break occurred. You can also examine variables using the Watch window.


Understanding Break Loops

Starting a Debugging Session
Using the Visual LISP Debugging Features
Continuable Break Loops
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features >
Understanding Break Loops

Expressions are the basic structural units of AutoLISP, and VLISP works by repeatedly reading, evaluating, and printing expressions. In LISP terminology, this is a read-eval-print loop.

When you are running an AutoLISP program without any debugging intervention by VLISP, you are running in the Top-Level read-eval-print loop. When you evaluate an expression within the VLISP Console window, and the normal prompt is displayed, you are also working at the Top Level.

When a program's evaluation is interrupted or suspended in the middle of execution, VLISP passes control to the Console and you enter a break loop. This break loop is a separate read-eval-print loop, and is nested underneath the original read-eval-print loop. It is possible to interrupt a break loop and start yet another read-eval-print loop beneath it. The nesting level of a break loop with respect to the Top Level is called the break level.

When you enter a break loop, VLISP prefixes the Console prompt with a number indicating the level where you are located. For example, when you first enter a break loop in a program, the prompt indicates this with the number 1:

_1_$

While you are in a break loop, you cannot switch control to the AutoCAD window.

On exiting from a break loop (for example, after issuing the Quit command), the current read-eval-print loop is terminated and the previous level loop is resumed. If you change the value of a variable in the break loop, this value will be used when the program resumes execution.

Topics in this section

  • Continuable Break Loops
  • Non-Continuable Break Loops


Continuable Break Loops

Understanding Break Loops
Understanding Break Loops
Non-Continuable Break Loops
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features > Understanding Break Loops >
Continuable Break Loops

There are continuable and noncontinuable break loops in VLISP. You can enter the continuable break loop at the very first break in program execution by any of the following methods:

  • Turning on the Stop Once mode and reaching an expression with debugging information (that is, an expression that is loaded from source code, as opposed to from a compiled .exe file)
  • Reaching a function marked for Debug on Entry
  • Reaching a breakpoint you set in the program
  • Entering a break loop by pressing the Pause button
  • Proceeding with a Step Over, Step Into, or Step Out command from the previous break loop state

When the program is interrupted, you enter the break loop. This is apparent if the VLISP Console window is active, because the prompt is changed to reflect the current level of the break loop. In this suspended state, you have read-write access to all variables in the environment in which the break occurred. For example, if the break occurred within a function containing several local variable declarations, those variables are accessible and you can change their values by issuing setq assignments at the Console prompt.

When stopped at a breakpoint, you can control subsequent program execution by choosing one of the following items from the Debug menu, or by pressing the equivalent toolbar button:

  • Reset to Top Level terminates all currently active break loops and returns to the Console top-level (the top read-eval-print loop).

  • Quit Current Level terminates the current break loop and returns to a break loop one level up. This may be another break loop or the top-level read-eval-print loop.

  • Continue resumes normal program execution from the breakpoint.

The Step commands evaluate portions of program code before resuming suspended mode:

  • Step Over looks for the close parenthesis matching the open parenthesis where the program is currently paused, and evaluates the expressions in between.

  • Step Into jumps into a nested expression, if any. If there are no nested expressions, it jumps to the next expression in sequence.

  • Step Out searches for the end of the function where the program is currently paused, and evaluates all the expressions up to that point.

After you exit the break loop to the Console top-level, the Console prompt returns to its original form (without a number prefix).


Non-Continuable Break Loops

Continuable Break Loops
Understanding Break Loops
Using Breakpoints
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features > Understanding Break Loops >
Non-Continuable Break Loops

A non-continuable break loop is activated when an error causes program interruption and the Break on Error option is set. In a non-continuable break loop, you can access all variables in the error environment, but you cannot continue program execution or execute any of the Step commands. To distinguish between continuable and non-continuable break loops, check to see if the Step and Continue toolbar buttons are active.

To leave a non-continuable break loop step, use either the Reset to Top-Level command to jump to the Console top-level loop, or Quit Current Level to return to the previous break loop level.

NoteIf you activate AutoCAD while in the midst of a non-continuable break loop, you will not be able to enter anything in the command window; in fact, the window will not contain a Command prompt. However, if you accidentally try typing anything in the AutoCAD command window, your keyboard input will be queued until AutoCAD regains control (that is, after you exit the break loop and activate the AutoCAD window). At that point, anything you typed is evaluated by AutoCAD as if you had just entered it at the Command prompt.


Using Breakpoints

Non-Continuable Break Loops
Using the Visual LISP Debugging Features
Changing Breakpoint Highlight Colors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features >
Using Breakpoints

Breakpoints allow you to mark a position in a program at which program execution should be interrupted. You can set breaks to occur before or after parenthetical expressions. Breakpoints can only be set from a VLISP text editor window.

To set a breakpoint

  1. Move the cursor to the position at which you want to halt execution. For example, to halt execution just before the open parenthesis of an expression, place the cursor just to the left of that open parenthesis.
  2. Choose the Toggle Breakpoint toolbar button or press F9 to set the breakpoint. (For variety, you can set a breakpoint by choosing Debug [image] Toggle Breakpoint from the VLISP menu, or by right-clicking the mouse and selecting Toggle Breakpoint from the resulting shortcut menu.)

    If you move the cursor to an ambiguous position, such as in the middle of an expression, VLISP will move the cursor to the nearest parenthesis and display the following message asking whether you agree with the breakpoint placement:

  3. Click Yes to accept the breakpoint location, or No if that is not where you want to set the break.To remove a breakpoint
  1. Position your cursor at the breakpoint you want to remove.
  2. Choose the Toggle Breakpoint toolbar button, or press F9.

    The Toggle Breakpoint works as an on/off switch. When no breakpoint exists, Toggle Breakpoint adds a break; if a breakpoint already exists at the cursor position, Toggle Breakpoint removes it. You can also use the Breakpoint Service dialog to remove breakpoints; see Listing and Viewing the Breakpoints in Your Program for information on this procedure.

  3. To remove all the breakpoints you have set, choose Debug [image] Clear All Breakpoints from the VLISP menu.

Topics in this section

  • Changing Breakpoint Highlight Colors
  • Disabling Breakpoints Temporarily
  • Listing and Viewing the Breakpoints in Your Program
  • Life Cycle of a Breakpoint


Changing Breakpoint Highlight Colors

Using Breakpoints
Using Breakpoints
Disabling Breakpoints Temporarily
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features > Using Breakpoints >
Changing Breakpoint Highlight Colors

VLISP marks each breakpoint position with a colored rectangle, so you can easily locate the breakpoints in your program. By default, active breakpoints are marked in red. You can change this color by setting the :BPT-ACTIVE option in Tools [image] Window Attributes [image] Configure Current. See Configure Current for more information on changing colors in VLISP windows.


Disabling Breakpoints Temporarily

Changing Breakpoint Highlight Colors
Using Breakpoints
Listing and Viewing the Breakpoints in Your Program
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features > Using Breakpoints >
Disabling Breakpoints Temporarily

When using multiple breakpoints within a source file, it may be useful to disable one or more breakpoints temporarily, but leave the breakpoint position defined for possible later use. This saves time over deleting and restoring the breakpoint.

To disable a breakpoint

  1. Place the cursor at the breakpoint marker and press the right mouse button.
  2. From the resulting menu, choose Breakpoint Service. VLISP displays the following dialog box:

  3. Click the Disable button in the Breakpoint Service dialog box to disable the breakpoint temporarily.

VLISP changes the color of the breakpoint marker when it disables the breakpoint. By default, it marks disabled breakpoints in blue. You can change this color by resetting the :BPT-DISABLE option.


Listing and Viewing the Breakpoints in Your Program

Disabling Breakpoints Temporarily
Using Breakpoints
Life Cycle of a Breakpoint
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features > Using Breakpoints >
Listing and Viewing the Breakpoints in Your Program

From the View menu, choose Breakpoints Window to see a list of all breakpoints currently defined to VLISP:

The Breakpoints dialog box lists the breakpoints in all programs you are editing in VLISP, not just the program in the active editor window. In the example above, only one program (yinyang) contains breakpoints. But you could have breakpoints set in any number of files.

Each entry in the Breakpoints dialog box shows the name of the source file containing the breakpoint, and the location of the breakpoint in the source. A leading + or - sign differentiates between active and disabled breakpoints. The dialog box allows you to delete all breakpoints at once or to edit (or display) one breakpoint at a time. Choose Show to display the source position of the breakpoint. The Edit button opens the Breakpoint Service dialog box, from which you can disable the breakpoint.


Life Cycle of a Breakpoint

Listing and Viewing the Breakpoints in Your Program
Using Breakpoints
Using Visual LISP Data Inspection Tools
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using the Visual LISP Debugging Features > Using Breakpoints >
Life Cycle of a Breakpoint

You can set breakpoints in a program either before or after you load the program. However, if you change the text in a program after loading the program, and then add a breakpoint, the breakpoint only takes effect after you reload the code.

Breakpoints remain in effect during the VLISP editing session and will survive between sessions if you choose Save Settings from the Tools menu.

In addition to removing breakpoints using the methods previously described in this chapter, program breakpoints are automatically lost when you do any of the following:

  • Delete the code fragment containing the breakpoint
  • Modify the file outside the VLISP editor (for example, edit and save it with Notepad)
  • Apply VLISP formatting commands to code fragments containing breakpoints

Note also that if you modify a program's code and run it without reloading it (with the Load Active Edit Window command), the program will be interrupted when a breakpoint is reached, but the exact source position will not be shown. The following dialog box indicates this situation has occurred:

To enable the proper display of a source position, you must reload the code and restart the program.


Using Visual LISP Data Inspection Tools

Life Cycle of a Breakpoint
Debugging Programs
Using the Watch Window
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs >
Using Visual LISP Data Inspection Tools

VLISP gives you almost unlimited access to symbols, values, and functions at any stage of program execution. The VLISP data inspection tools are implemented as modeless windows (except for the Symbol Service dialog box), meaning they stay on the screen as long as you need them, no matter what your program does.

  • The Watch window displays the current value of any set of variables.
  • The Trace Stack window displays the most current call hierarchy. At any level of the stack you can view the corresponding code, the calling code, the local variables, and more.
  • The Symbol Service dialog box displays the current value of a symbol as well as its current flags. You can modify both the value and the flags from here.
  • Inspect windows display any LISP object (from a string to an AutoCAD block definition) to any level of detail needed.
  • Frame Binding windows display the values of all local variables for their particular stack frame (that is, the specific function invocation in the call sequence).

VLISP provides a logging feature that, when active, allows you to copy the contents of a Data Inspection window to a log file.

To turn trace logging on and off

  1. Activate the Trace window.
  2. Specify a log file by choosing File [image] Toggle Trace Log from the VLISP menu. Note that if the Trace window is not active, the Toggle Trace Log option will not be available.
  3. Choose Save to select the file you specified. If the file already exists, VLISP prompts you with the following message:

    If you reply Yes, VLISP appends new data to the current contents of the file. If you reply No, VLISP overwrites the file and its original contents will be lost. Choose Cancel to terminate the operation and specify a different file name.

  4. To close the log file and quit the logging process, choose Toggle Trace Log from the File menu again.

When Trace logging is turned on, any information displayed in the Trace window is also written to the log file. Most VLISP data inspection tools provide a toolbar button for copying data to the Trace window.

The state of Trace logging is indicated in the Trace window's title bar. If logging is in effect, VLISP displays the name of the log file in the title bar. If logging is off, no file name appears in the title bar.

If you do not close the log file before exiting VLISP, it closes the file automatically upon exit. After a log file is closed, you can view its contents with any text editor, such as the VLISP text editor.

Topics in this section

  • Using the Watch Window
  • Understanding the Trace Stack Window
  • Using the Symbol Service Dialog Box
  • Using Inspect Windows
  • Viewing AutoCAD Drawing Entities


Using the Watch Window

Using Visual LISP Data Inspection Tools
Using Visual LISP Data Inspection Tools
Using the Watch Toolbar
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools >
Using the Watch Window

The Watch window monitors the values of AutoLISP variables during program execution. Each Watch window element line displays the name of a variable and its current value, as illustrated in the following figure:

The Watch window is updated at each step of a VLISP interactive session and always shows the current environment state. In debugger mode, the Watch window is refreshed automatically at the end of every expression evaluation.

To add variables to the Watch window

  1. Highlight the variable name in any VLISP context (that is, in a text editor window, the Console window, etc.).
  2. Choose the Add Watch button, or choose Add Watch from the Debug menu. You can also select Add Watch from a shortcut menu by right-clicking the mouse while the cursor is on a variable name.

  3. If the Watch window is already active, you can add variables to the watch list by clicking the Add Watch button on the toolbar in the Watch window.

    If VLISP cannot determine which variable you are interested in based on the cursor position or the text you've selected, it displays the Add Watch window:

    Specify the name of the variable to be watched in this window, then click OK.

The Watch window retains its variables during a VLISP session. This means that if you invoke Watch, add variables to the Watch window, and then close the Watch window, the variables you added will appear in the Watch window, if you invoke Watch again during the current session.

The introductory section of this chapter includes an example of using the Watch window. (See Monitoring the Evaluation Results of an Expression.)

Topics in this section

  • Using the Watch Toolbar
  • Using the Watch Item Shortcut Menu


Using the Watch Toolbar

Using the Watch Window
Using the Watch Window
Using the Watch Item Shortcut Menu
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using the Watch Window >
Using the Watch Toolbar

The toolbar on the Watch window contains the following buttons:

Add Watch

Invokes the Add Watch command to add a new variable to the Watch window. This variable can be selected from any active text window or typed in the Add Watch dialog box.

Clear Window

Removes all variables from the Watch window.

Sort Expressions

Sorts the variables in the Watch window alphabetically by name.

Copy to Trace/Log

Copies the contents of the Watch window to the Trace window. If logging is active, the contents of the Watch window are also copied to the trace log.


Using the Watch Item Shortcut Menu

Using the Watch Toolbar
Using the Watch Window
Understanding the Trace Stack Window
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using the Watch Window >
Using the Watch Item Shortcut Menu

To display the Watch Item shortcut menu, select an item in the watch list and right-click.

The following items appear on the Watch Item menu:

Inspect Value

Invokes the Inspect feature for the selected value. (See Using Inspect Windows.)

Copy Value

Copies the value of the selected variable into the IDE global variable *obj*.

Print Value

Prints the selected variable value in the Console window, prefixed with a single quote (').

Symbol

Calls the Symbol Service dialog box for the selected variable. (See Using the Symbol Service Dialog Box.)

Apropos

Calls the Apropos dialog box using the selected symbol's name as the Apropos argument.

Remove from Watch

Removes the selected variable from the Watch window.


Understanding the Trace Stack Window

Using the Watch Item Shortcut Menu
Using Visual LISP Data Inspection Tools
Stack Element Lists
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools >
Understanding the Trace Stack Window

VLISP has a special debugging tool called a trace stack which is a historical record of the execution of functions within your program. (The term stack is derived from a computer programming structure of the same name.) The following figure illustrates adding and removing items from a stack. You can see why a stack structure is often referred to as LIFO—Last In, First Out:

The trace stack is used by VLISP to “remember its way out” of a nested series of expressions. By viewing the stack, you can see what is happening within your program as it is executing (within a suspended break mode) or immediately after it has crashed.

Before you invoke a function at the Console window or from AutoCAD, the trace stack is empty. The action of invoking a function causes a record, or element, to be placed on the stack. As that function calls additional nested functions to perform the work of your program, additional elements may be added to the stack. VLISP only needs to place elements on the stack when it needs to remember its way out of nested functions.

There are two conditions where it is useful to examine trace stacks. The first is when your program is in a suspended state, such as during a breakpoint pause. The second is after an error occurs, causing your program to fail.

Topics in this section

  • Stack Element Lists
  • Viewing the Current Trace Stack
  • Displaying Information on a Trace Stack Element
  • Using the Frame Binding Window
  • Understanding Keyword Frames
  • Understanding Special Function Call Frames
  • Viewing an Error Trace Stack


Stack Element Lists

Understanding the Trace Stack Window
Understanding the Trace Stack Window
Viewing the Current Trace Stack
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Stack Element Lists

A stack element is an individual record or line-item history within a trace stack. There are five kinds of elements that may appear within a stack:

  • Function call frames show one individual function invocation. Each function call frame appears in the following format:

    level (function-name {argument1}...)

    Arguments within this listing are displayed not by their local parameter name, but by the values that were actually passed to the function.

  • Keyword frames are displayed at the very top and bottom of a trace stack. They are displayed in the following form:

    level :keyword - {optional-data}

    The keyword indicates the type of the frame. The optional-data displays additional information relating to the state of the program.

  • Top forms indicate an action that was initiated by typing an expression at the top-level Console window, or from the invocation of a function that was triggered during the loading of a file or selection within a VLISP editor window.
  • Lambda forms are placed within a stack whenever a lambda function is encountered within your program.
  • Special forms display the invocation of the foreach and repeat functions. The arguments for these functions are not displayed. They appear as:

    level (function-form ...)

Function call frames and keyword frames are discussed in more detail in the following sections. These sections use the following code to demonstrate the trace stack. If you wish, you can copy this code into a VLISP editor window, set a breakpoint as indicated in the code comments, and run this sample:

(defun stack-tracing (indexVal maxVal)
   (princ "At the top of the stack-tracing function, indexVal = ")
   (princ indexVal)
   (if (< indexVal maxVal)
      (stack-tracing (1+ indexVal) maxVal)
      (princ "Reached the maximum depth.") ; place a breakpoint
                                          ; at the beginning of
                                          ; this line
   )
)
(defun c:trace-10-deep ()
   (terpri)
   (stack-tracing 1 10)
)


Viewing the Current Trace Stack

Stack Element Lists
Understanding the Trace Stack Window
Displaying Information on a Trace Stack Element
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Viewing the Current Trace Stack

To see the state of a function call stack while your program is suspended at a breakpoint, choose View [image] Trace Stack from the VLISP menu, or click the Trace toolbar button. VLISP displays the Trace Stack window:

The Trace Stack window displayed above shows a function call frame for the stack-tracing function. The second element, or frame, in the trace stack is highlighted:

[2] (STACK-TRACING 10 10)

The number [2] simply identifies it as the second element in the stack. The numbers following the stack-tracing function name (10 10) indicate the actual values that were passed to the function.


Displaying Information on a Trace Stack Element

Viewing the Current Trace Stack
Understanding the Trace Stack Window
Using the Frame Binding Window
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Displaying Information on a Trace Stack Element

To obtain more information about an element in the trace stack, select the element and right-click to display a shortcut menu.

Active items available on the shortcut menu depend on the type of stack element you selected before right-clicking. Possible menu commands include the following:

Inspect

Calls the Inspect feature for the selected stack element.

Print

Prints the stack element to the Console window.

Function Symbol

Calls the Symbol Service feature for the function call in the stack frame, if the function is called by the symbol.

Copy

Copies the selected trace stack element to the IDE global variable *obj*.

Local Variables

Displays the Frame Bindings dialog box to allow browsing of local variable values at the time the function was called; see Using the Frame Binding Window.

Source Position

Checks whether or not the source text is available for the function called at the selected stack frame. If the source code is available, the text window with the source code is displayed, with the current position inside the function highlighted.

Call Point Source

Shows the position of the caller expression, similar to Source Position.


Using the Frame Binding Window

Displaying Information on a Trace Stack Element
Understanding the Trace Stack Window
Understanding Keyword Frames
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Using the Frame Binding Window

Choose the local variables item from the Trace Stack shortcut menu to display the Frame Binding window:

The Frame Binding window displays information about the local variables in the frame. In the example shown above, the parameter names (INDEXVAL, MAXVAL) are listed, along with the values assigned to these parameters. These values were passed to the function. The parameters are listed in the order they are defined within the function.

If you right-click on an entry in the Frame Binding window, VLISP displays a shortcut menu containing the following items:

Inspect

Calls the Inspect feature for the selected value.

Print

Displays the selected value in the Console window.

Symbol

Calls the Symbol Service dialog box for the selected symbol.

Copy

Copies the selected value into the IDE global variable*obj*.

Add to Watch

Adds the selected symbol to a Watch window.


Understanding Keyword Frames

Using the Frame Binding Window
Understanding the Trace Stack Window
Understanding Special Function Call Frames
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Understanding Keyword Frames

A keyword frame indicates a specific type of operation that occurs within the VLISP environment. The keyword indicates the type of operation. Keyword frames will appear in only two locations: at the very top of the stack, or at the very bottom of the stack.

The following types of keyword frames will appear only at the bottom of a stack:

Keyword frames (bottom)
Frame type | Operation that occurred
:ACAD-REQUEST | A call to the function shown in the frame immediately above the :ACAD-REQUEST keyword frame was invoked from the AutoCAD command prompt.
:DCL-ACTION | Execution of a DCL tile or dialog action was requested from AutoCAD. The keyword :DCL-ACTION is followed by two strings: the DCL dialog name and the value of the $KEY variable in the DCL action body. If a number appears, it is the value of the $REASON variable in the DCL action body. The frame immediately above the keyword describes the function call built from the action string.
:INSPECT-EVAL | Evaluation of an Inspect command.
:INSPECT-VERBOSE | Entrance into a drawing Inspect hook function.
:TOP-COMMAND | The VLISP IDE requested the action resulting in the first element placed within the stack. This situation occurs, for example, when a function is invoked directly from loading a selection or a file.
:USER-INPUT | The character string shown in the frame was entered from the VLISP Console window. The frame immediately above the keyword describes the expression as it was translated from the user input. If the input string is too long, right-click to open a shortcut menu, and choose Show Message to view the entire text. You can also choose the Inspect command to inspect the entered string.
:WATCH-EVAL | Evaluation of a watch expression.

The following types of keyword frames may appear at the top of a stack:

Keyword frames (top)
Frame type | Operation that occurred
:ACMD-CALLBACK | Registered AutoCAD command call.
:AFTER-EXP | Indicates that your program is interrupted in a debugging break mode, and the Step Into or Step Over command just stepped out of an expression.
:ARQ-SUBR-CALLBACK | Indicates a normal call from AutoCAD to a VLISP-defined function.
:AXVLO-IO-CALLBACK :DWF :DWG | Saves or restores a VL object in a DWG.
:BEFORE-EXP | Debugger break upon entering the function. This message will appear whenever you are stepping through using Step Into or Step Over, and the step is entering an expression (as opposed to just leaving an expression, which is indicated by the :AFTER-EXP keyword).
:BREAK-POINT | User-specified breakpoint.
:ENTRY-NAMESPACE | A call in the context of a separate-namespace VLX.
:ERROR-BREAK | General runtime error. The Show Message shortcut menu selection allows you to view more specific error messages.
:FUNCTION-ENTRY | Debugger break upon entering the function. The stack element following this message contains the call frame for the function in which the break occurred.
:KBD-BREAK | The PAUSE key was pressed, placing the program on hold.
:PROTECT-ASSIGN | Assignment of a value to a protected symbol. From the right-click shortcut menu, you can choose Show Message to view the variable name, the current value, and the new value that was attempted to be assigned to the variable. You can also choose the Inspect command to view the list containing the symbol, and the new value indicated following :PROTECT-ASSIGN.
:REACTOR-CALLBACK | Reactor call.
:READ-ERROR | Error during a read operation. The Show Message shortcut menu selection provides additional information about the error.
:SYNTAX-ERROR | VLISP encountered incorrect AutoLISP program syntax.


Understanding Special Function Call Frames

Understanding Keyword Frames
Understanding the Trace Stack Window
Viewing an Error Trace Stack
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Understanding Special Function Call Frames

There are two special function call frames.

The FOREACH frame indicates a call to the foreach function. From the shortcut menu, choose the Local Variables option to display the name and current value of the user-supplied variable and list variables bound by the foreach function. For example, if the following expression were evaluated

(foreach n '(a b c) (print n))

then selecting the Local Variables option displays a Frame Binding window like the following:

This Frame Binding window identifies the user-supplied variable (N), the current value of that variable (A), and the items remaining to be processed in the list supplied to foreach (BC).

The REPEAT frame indicates a call to the repeat function. From the shortcut menu, the Local Variables command displays the special name counter and the current value of the repeat internal counter. The internal counter value is initially set to the integer value passed to repeat, indicating the number of iterations desired. The counter decreases by one at each loop iteration. It shows the number of iterations remaining, minus one.

Note that each repeat expression possesses its own counter, but only one such counter can be added to the Watch window.

AutoLISP functions such as if, cond, and, and setq do not appear on the stack. They are not necessary because their call position may be viewed within the source file in the VLISP text editor window.


Viewing an Error Trace Stack

Understanding Special Function Call Frames
Understanding the Trace Stack Window
Using the Symbol Service Dialog Box
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Understanding the Trace Stack Window >
Viewing an Error Trace Stack

If your program terminates due to an error, choose Error Trace from the View menu to see the state of function invocations up to the time your program crashed:

The error trace is a copy of the trace stack as it appeared at the time the error occurred. If the Break on Error debugging option is selected, the error trace and the trace stack are identical immediately after an error occurs. You can see this by selecting Break on Error from the Debug menu, intentionally causing an error (for example, issuing a function call that divides by zero), and opening the two trace windows.

The toolbar on the Trace Stack window contains two buttons:

Refresh

Refreshes contents of Trace Stack window.

Copy to Trace/Log

Copies the window contents to the Trace Stack window or open log file.

When you issue a Reset command to exit a break loop (for example, Reset to Top Level), pressing the Refresh button in the Trace Stack window replaces that window's contents with the latest trace stack data. In contrast, refreshing the Error Trace window does not change the window's contents, unless a subsequent error has occurred.


Using the Symbol Service Dialog Box

Viewing an Error Trace Stack
Using Visual LISP Data Inspection Tools
Using the Symbol Service Toolbar
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools >
Using the Symbol Service Dialog Box

The Symbol Service feature is designed to simplify access to the different debugger features provided for symbols. Most facilities available for symbols are also available through this feature.

To open a Symbol Service dialog box and update a symbol

  1. Highlight the name of any symbol in your program's source code or in the Console window.

  2. Choose View [image] Symbol Service from the VLISP menu, or press the Symbol Service button on the Debug toolbar.

    The Symbol Service dialog box contains the following components:

    • A toolbar
    • A Name field, where you can enter or change the symbol to work on
    • A Value field that displays the symbol's value or its initial substring
    • A series of check boxes for symbol flags
  3. To update the value of the displayed symbol, enter an expression in the Value field. When you press OK, VLISP evaluates the expression and assigns its value to the symbol.

If the symbol you specified is a protected symbol, the Value field will be read-only. To remove protection, clear the Protect Assign check box. See Understanding Symbol Flags for more information on Protect Assign.

Use the OK and Cancel buttons to close the dialog box and to continue working in VLISP.

Topics in this section

  • Using the Symbol Service Toolbar
  • Understanding Symbol Flags


Using the Symbol Service Toolbar

Using the Symbol Service Dialog Box
Using the Symbol Service Dialog Box
Understanding Symbol Flags
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using the Symbol Service Dialog Box >
Using the Symbol Service Toolbar

The Symbol Service toolbar contains the following buttons:

Watch

Adds the symbol to the Watch window.

Inspect

Opens the Inspect window to show the value of the symbol.

Show Definition

If the symbol names a user-defined function, this command opens the text editor window containing the function definition and highlights the function.

Help

Displays information from the VLISP Help file, if the symbol refers to a built-in function.


Understanding Symbol Flags

Using the Symbol Service Toolbar
Using the Symbol Service Dialog Box
Using Inspect Windows
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using the Symbol Service Dialog Box >
Understanding Symbol Flags

The Symbol Service dialog box provides direct access to symbol flags and properties of functional objects that may be associated with them. The following symbol flag options are available:

Trace (Tr)

The Trace flag activates the tracing of any user-defined function (shown as a symbol within the Symbol Service window). Tracing will only occur when the symbol is a function, and the expression being evaluated uses the symbol name as a function (not as a local variable name, for example).

Protect Assign (Pa)

This flag intercepts attempts to assign values to protected symbols. For instance, the symbol pi is a protected symbol. All symbols that are the names of built-in AutoLISP functions are assignment-protected by default. See Protected Symbols for more information on symbol protection.

Note that symbol protection works only for explicit setq, set, or defun invocations. Binding a protected symbol in an argument list of a user-defined function is not intercepted.

Debug on Entry (De)

If this flag is set, a breakpoint occurs at each function invocation, regardless of whether the function was loaded with debugging information. The De flag is tested at each function invocation, not during load or defun execution.

Note that VLISP ignores the Debug-on-Entry flag for all SUBR and EXRXSUBR symbols.

Export to ACAD (Ea)

If the Ea flag is set, the function associated with this symbol is defined as an external subroutine. This makes the function available to ObjectARX applications.


Using Inspect Windows

Understanding Symbol Flags
Using Visual LISP Data Inspection Tools
Using the Inspect Window
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools >
Using Inspect Windows

The Inspect feature is the component of VLISP that provides you with the ability to browse, examine, and modify AutoLISP and AutoCAD objects. You can use Inspect to view the following items:

  • Any AutoLISP objects such as lists, numbers, strings, and variables
  • AutoCAD drawing entities
  • AutoCAD selection sets

Using Inspect, you can also browse through complex data structures.

The Inspect tool creates a separate window for each object you inspect.

To open an Inspect window

  1. Select an AutoLISP object name (for example, a variable).

  2. Choose View [image] Inspect from the VLISP menu, or press the Inspect button on the Debug toolbar.

    The Inspect command is also available from a number of shortcut menus and from the windows displayed by the Apropos and Symbol Service features.

  3. If you invoke the Inspect command without selecting an object name, VLISP prompts you to specify the object you want to inspect, displaying the following dialog box:

    Enter the object or expression you want to inspect, then press OK to open the Inspect window or press Cancel to cancel the action.

VLISP saves the last 15 items you enter in the Inspect prompt box. You can choose a previously specified object for inspection by selecting it from the drop-down list.

For example, to inspect the definition of the yinyang function, select the name in the text editor window containing the yinyang.lsp, then press the Inspect button to view the Inspect window:

Topics in this section

  • Using the Inspect Window
  • Understanding Object Element List Formats
  • Common Inspect Commands
  • Copying Inspect Objects to the *obj* IDE Global Variable
  • Handling Errors in the Inspect Command
  • Closing All Inspect Windows


Using the Inspect Window

Using Inspect Windows
Using Inspect Windows
Understanding Object Element List Formats
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using Inspect Windows >
Using the Inspect Window

All Inspect windows have a similar appearance and contain a caption, an object line, and an object element list (which may be empty). The window elements contain the following content:

  • The caption of an Inspect dialog box shows the type of object being inspected.
  • The object line shows a printed representation of the inspected object.
  • The element list displays the components of the inspected object.

The element list may vary in size and content for different object type. Each element list is shown as a pair: name and content. The name is enclosed in brackets. Square brackets ([]) denote that you can modify the item by issuing a Modify command from the shortcut menu associated with the item, and curly brackets ({}) indicate that you cannot modify the item.

Both the object line and the element list lines have their own associated shortcut menus. These menus are described in Common Inspect Commands.

VLISP will display up to 50 element lines in an Inspect window. If there are more than 50 elements to be shown, Inspect displays the elements in a series of pages. When you scroll to the bottom of the Inspect window and there are more entries remaining to be displayed, the bottom of the list contains a ">>>[Next page]" element line. To navigate among the pages, use the following procedures:

  • To page down, double-click on the ">>> [Next page]" element line, or select that line and press ALT + E.
  • For Inspect windows showing AutoLISP lists and selection sets, you can page up by double-clicking the "<<<[Previous page]" element line, which appears at the top of the list. (Or select that line and press ALT + E.)
  • For AutoLISP lists and selection sets, when you reach the last page of element lines, you can return to the first page by double-clicking on the "<<<[First page]" element line, or by selecting that line and pressing ALT + E.

VLISP expands an item in the element list if you double-click on it. For example, the {Auxiliary} component in the sample Inspect window is itself a list. Double-click on the {Auxiliary} item to open another Inspect window showing the elements in the list:


Understanding Object Element List Formats

Using the Inspect Window
Using Inspect Windows
Common Inspect Commands
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using Inspect Windows >
Understanding Object Element List Formats

The contents of an Inspect element list vary, depending on the data type of the object being inspected. The following table identifies the list contents for each data type.

Inspect element lists
Data type | Contents of element list
INT (integer) | The various representations of integers.
REAL (floating point number) | Empty.
STRING | The sequence of characters in the string, which may in turn be inspected as integers.
SYMBOL | Three elements: value, print name, and flags.
LIST (for proper lists) | Items of the inspected list.
LIST (for improper lists) | Two elements: the car and cdr fields. It serves for all cases that are not proper LISP lists, that is, where the last cdr is not nil.
FILE | The name of the corresponding file and the file's opening attributes.
SUBR, EXRXSUBR, and USUBR | The name of the function (the name that was specified in defun or at load time). SUBR refers to internal and compiled functions, EXRXSUBR refers to external ARX functions, and USUBR identifies user-defined functions.
ENAME (drawing entity) | The fields in this element list correspond to the AutoCAD DXF object list, as returned by the AutoLISP built-in function.
PICKSET (selection set) | List of selected AutoCAD objects.
VARIANT | The data type and value of the variant.
SAFEARRAY | The data type, number of dimensions, and value of the safearray.

Sample Inspect windows for each data type follow.

INT

The INT (integer) Inspect window shows the number represented in binary, octal, decimal, hexadecimal, and character formats. Character format means the ASCII character that corresponds to the number (for large numbers it takes the last byte).

The INT Inspect window does not have an element list.

REAL

The REAL Inspect window does not have an element list.

STRING

Shows the string as a list of characters represented as numbers:

Double-click on a listed character to see its number representation.

SYMBOL

Contains the symbol name, the symbol value, and the flags that represent symbol attributes. Flags may be one of the following:

Pa Protect Assign

Tr Trace

De Debug on entry

Ea Export to ACAD

To change a symbol's value or flag settings, use the object line menu command Symbol Service, which shows the Symbol Service window.

Note that the information supplied by the SYMBOL Inspect window is available more conveniently through the Symbol Service feature.

LIST (properlist)

Shows the elements of a proper list:

LIST (improperlist)

Shows the car and cdr of an improper list. For example, a list constructed by (cons 4 '(5 . 0)) is represented as follows:

FILE

File Inspect fields include the following:

File name is the name string used in the open function.

Mode indicates whether the file is open for input, output, append, or whether the file is closed.

ID shows the internal file identifier.

Position shows the current position in the file.

EOF indicates whether or not the end of the file has been reached. This field does not appear if a file is open for output.

SUBR

The SUBR data type represents functions that cannot be debugged with the VLISP debugging tools (for example, you cannot set breakpoints). These are internal AutoLISP functions, or functions loaded from FAS or VLX files.

The SUBR Inspect window shows a string containing the name of the symbol, as in the following example:

USUBR

The USUBR data type represents functions that can be debugged with the VLISP debugging tools (for example, you can set breakpoints and view the values of program variables). These functions are loaded from LISP source code.

The USUBR Inspect window shows the name of the symbol, a list of function parameters (arguments), and a list of local variables declared in the function (listed after the “/” in the defun argument list). The following example shows an Inspect window for a function that accepts no arguments and declares several local variables:

EXRXSUBR

The EXRXSUBR data type represents functions loaded from external ARX applications. The EXRXSUBR Inspect window shows a string containing the function name, as in the following example:

ENAME

The contents of the ENAME Inspect window depend on the properties of the entity being inspected. The following example shows an Inspect window for a circle:

PICKSET

The PICKSET Inspect window lists the elements in a selection set:

VARIANT

The VARIANT Inspect window shows the data type and value of the variant. The following example shows an Inspect window for a variant that contains an array of doubles:

SAFEARRAY

The SAFEARRAY Inspect window shows the data type, number of dimensions, and value of the safearray. The following example shows a Safearray Inspect window for a single dimension array of doubles:

You can also use the Inspect feature to examine ActiveX® objects. See Using the Inspect Tool to View Object Properties for an example of this.


Common Inspect Commands

Understanding Object Element List Formats
Using Inspect Windows
Copying Inspect Objects to the *obj* IDE Global Variable
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using Inspect Windows >
Common Inspect Commands

The Inspect windows provide shortcut menus containing commands relevant to the data being inspected.

To display the object line shortcut menu, press ALT + 0, or right-click the object line. The following commands may be present in an object line shortcut menu:

Symbol Service

Invokes the Symbol Service feature.

Print (ALT + P)

Prints the object in the Console window.

Pretty Print

Formats and prints the object in the Console window.

Copy

Copies the object to the *obj* variable.

Log

Copies the current contents of the Inspect dialog box to the Trace window. If logging is active, the contents are also copied to the trace log.

Update (ALT + U)

Updates the Inspect dialog box to show the most recent status of the inspected object.

The element line shortcut menu appears after highlighting the element line and right-clicking. The following commands may appear on the element line shortcut menu:

Inspect (ALT + I)

Calls Inspect and passes it the element value as an argument.

Descend (ALT + D)

Calls Inspect, passes it the element value as an argument, and closes the current Inspect window.

Copy

Copies the value of the inspected element to the *obj*variable.

View Source

Activates a text editor window containing the selected text. If the text was loaded from the Console window or from a list representation, this command activates a new text editor window.

The default command for an element line, invoked by pressing ENTER, is the Inspect command.


Copying Inspect Objects to the *obj* IDE Global Variable

Common Inspect Commands
Using Inspect Windows
Handling Errors in the Inspect Command
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using Inspect Windows >
Copying Inspect Objects to the *obj* IDE Global Variable

Sometimes it is useful to access some part of an object from your program or from the VLISP Console window. You may also want to copy the value of one object's item into another item and so on. To perform all these tasks, the Inspect feature manages a reserved global IDE variable named *obj*. This variable can be used as a temporary storage area while browsing through data structures. From inside an Inspect dialog box, you can assign a value to this variable and replace the value of the current item with the value of *obj*.

To assign the value of an inspected object to the *obj* variable, right-click the item in the Inspect window and choose Copy.


Handling Errors in the Inspect Command

Copying Inspect Objects to the *obj* IDE Global Variable
Using Inspect Windows
Closing All Inspect Windows
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using Inspect Windows >
Handling Errors in the Inspect Command

In text editor windows it is not possible to inspect selected expressions longer than 256 characters. If you select a string longer than 256 characters, you will be prompted to enter an object name.

If you specify an object or expression that VLISP cannot evaluate, VLISP issues a standard AutoLISP error message. Once the error message appears, you can correct the expression in the dialog box and try to evaluate it once more.

Errors arising from evaluation of the object you entered cannot be investigated from a nested break loop, because all breaks are disabled during such evaluation. If you wish to examine the error, choose View [image] Error Trace from the VLISP menu, or copy the expression to the Console prompt and press ENTER.


Closing All Inspect Windows

Handling Errors in the Inspect Command
Using Inspect Windows
Viewing AutoCAD Drawing Entities
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Using Inspect Windows >
Closing All Inspect Windows

To close all Inspect windows, choose Window [image] Close Windows [image] Inspectors from the VLISP menu.


Viewing AutoCAD Drawing Entities

Closing All Inspect Windows
Using Visual LISP Data Inspection Tools
Viewing Entities in the Drawing Database
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools >
Viewing AutoCAD Drawing Entities

VLISP provides facilities to walk through the AutoCAD drawing database and inspect the raw data for each drawing entity reported by AutoCAD. You access drawing entities through the VLISP Browse Database feature. Browse Database displays entity information in Inspect windows. You can set a diagnostic option telling VLISP how much information to supply about entities.

To control the amount of Inspect information displayed for drawing objects

  1. Choose Tools [image] Environment Options [image] General Options.
  2. Click the Diagnostic tab in the General Options window.
  3. Select Inspect Drawing Objects Verbosely to view detailed entity information. Clear the option check box to minimize the amount of information supplied by Inspect.

Topics in this section

  • Viewing Entities in the Drawing Database
  • Viewing Symbol Tables in the Drawing Database
  • Viewing Blocks in the Drawing Database
  • Viewing Selected Objects in a Drawing
  • Viewing Extended Data


Viewing Entities in the Drawing Database

Viewing AutoCAD Drawing Entities
Viewing AutoCAD Drawing Entities
Viewing Symbol Tables in the Drawing Database
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Viewing AutoCAD Drawing Entities >
Viewing Entities in the Drawing Database

To Open an Inspect window for the collection of entities in the current drawing database, choose View [image] Browse Drawing Database [image] Browse All Entities from the VLISP menu. VLISP displays a window listing the entities in the database:

Note that VERTEX and ATTRIB entity types are not included in this list. You access these entity types through their parent entities, which are available when you inspect POLYLINE and INSERT entities.

The shortcut menu commands available for the object line in the AutoCAD Entities Inspect window are Log and Update.

To open an Inspect window for a specific entity, double-click on the entity name, or select the entity, then right-click, and choose Inspect:

The title bar of this window identifies the drawing entity type. The object line of the window displays the entity name.

<Entity name: 1cdf190>

The shortcut menu for the object line contains the common Inspect commands Print, Copy, Log, and Update, plus some new items.

Modify

If available, this command opens the standard AutoCAD DDMODIFY dialog for the inspected entity.

Inspect Raw Data

Displays an Inspect window containing the list resulting from an entget function call for the entity.

Inspect Next Entity

Displays an Inspect window for the next entity in the entities list.

Inquire Extended Data

Displays a list of applications currently registered by regapp. If you select an item from the list, any extended data related to the chosen application is included in the Inspect entget list. See Viewing Extended Data for more information.


Viewing Symbol Tables in the Drawing Database

Viewing Entities in the Drawing Database
Viewing AutoCAD Drawing Entities
Viewing Blocks in the Drawing Database
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Viewing AutoCAD Drawing Entities >
Viewing Symbol Tables in the Drawing Database

Choosing View [image] Browse Drawing Database [image] Browse Tables from the VLISP menu opens an Inspect window for the collection of symbol tables in your drawing:

You can inspect each table as a collection of named attributes. Double-click on a name to view its attributes, or select the name, right-click, and choose Inspect:

To view a table entry for a selected attribute, double-click on the attribute name, or select the attribute, right-click, and choose Inspect:


Viewing Blocks in the Drawing Database

Viewing Symbol Tables in the Drawing Database
Viewing AutoCAD Drawing Entities
Viewing Selected Objects in a Drawing
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Viewing AutoCAD Drawing Entities >
Viewing Blocks in the Drawing Database

Choose View [image] Browse Drawing Database [image] Browse Blocks from the VLISP menu to open an Inspect window for the blocks in your drawing:

Double-click on the block name you are interested in to open an Inspect window for the block, or select the block, right-click, and choose Inspect.

The raw-data element shows the symbol table entries for the inspected block. Double-click on the parts item to open an Inspect window listing the collection of entities residing within the block.

The raw-data and parts element lines occur in all block Inspect windows. Other element lines, such as {name}, appear only if the Inspect Drawing Objects Verbosely Diagnostic option is selected. See Diagnostic Tab (General Options Dialog Box) for information on setting VLISP diagnostic options.


Viewing Selected Objects in a Drawing

Viewing Blocks in the Drawing Database
Viewing AutoCAD Drawing Entities
Viewing Extended Data
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Viewing AutoCAD Drawing Entities >
Viewing Selected Objects in a Drawing

Choose View [image] Browse Drawing Database [image] Browse Selection from the VLISP menu to select the drawing objects you want to view. VLISP invokes the ssget function to prompt you to define a selection set in the AutoCAD drawing window. When you complete the selection, VLISP opens the Inspect window for your selection:

Double-click on an entity name to open an Inspect window for the entity, or select an entity, right-click, and choose Inspect.


Viewing Extended Data

Viewing Selected Objects in a Drawing
Viewing AutoCAD Drawing Entities
Building Applications
AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Using Visual LISP Data Inspection Tools > Viewing AutoCAD Drawing Entities >
Viewing Extended Data

Choose View [image] Browse Drawing Database [image] Inquire Extended Data from the VLISP menu to see a list of the applications currently registered (through regapp) as containing extended data. If you select an application from this list, its extended data is included into the Inspect entget list.

To view extended data associated with an AutoCAD object

  1. Choose View [image] Browse Drawing Database [image] Inquire Extended Data from the VLISP menu.
  2. Select the application whose data you are interested in viewing.
  3. In the AutoCAD window, select the drawing objects whose extended data you want to view.
  4. From the VLISP menu, choose View [image] Browse Drawing Database [image] Browse Selection. VLISP displays an Inspect window listing the AutoCAD objects you selected:

  5. In the Inspect window element list, double-click on an object whose extended data you want to view. VLISP displays an Inspect window for the object.
  6. Select the object line in the Inspect window and right-click to view a shortcut menu.
  7. Choose Inspect Raw Data from the shortcut menu. VLISP displays an Inspect window like the following:

    Extended data is identified by the -3 DXF group code. The last line in the entity list shows the extended data for the selected object. You can double-click on this line to open a separate Inspect window containing just the extended data.


Building Applications

Viewing Extended Data
Using the Visual LISP Environment
Compiling and Linking Programs
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Building Applications

You can compile your program files and create a single executable module that you can distribute to users.

This chapter describes how to build applications with Visual LISP®.

VLISP allows you to compile your program files and create a single executable module that you can distribute to users. The first part of this chapter provides basic knowledge about the VLISP compiler and may be sufficient for building macros and small programs that work in a single document. The rest of the chapter helps you build more complex applications. These remaining sections discuss design considerations for an environment where several AutoCAD® drawings may be open at the same time, and provide information on fine-tuning the performance of compiled code.

Topics in this section

  • Compiling and Linking Programs
  • Making Application Modules
  • Designing for a Multiple Document Environment


Compiling and Linking Programs

Building Applications
Building Applications
Using the Compiler
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications >
Compiling and Linking Programs

Each time you load AutoLISP® source code, the code is translated into instructions the computer understands (executable code). The advantage of having source code translated each time you load it is that you can make a change and immediately try it out. This is useful for quickly testing new code, and for debugging that code.

Once you are sure your program is working correctly, translating AutoLISP source code each time it loads is time-consuming. VLISP provides a compiler that generates executable machine code files from your source files. These executable files are known as FAS files. Because the executable files contain only machine-readable code, the source code you spent weeks or months developing remains hidden even if you distribute your program to thousands of users. Even strings and symbol names are encrypted by the VLISP file compiler.

VLISP also provides features for packaging more complex AutoLISP applications into VLISP executable (VLX) files. VLX files can include additional resources files, such as VBA and DCL files, and compiled AutoLISP code. See Making Application Modules for instructions on building VLX files.

Using VLX files, you can further control your application's operating environment by exposing only those functions you choose to expose, and by maintaining a wall between your program's variables and the variables users can interact with in AutoCAD. For more information on controlling the operating environment of a VLX, see Designing for a Multiple Document Environment.

Topics in this section

  • Using the Compiler
  • Compiling a Program from a File
  • Walking through a Compile Example
  • Loading and Running Compiled Programs
  • Linking Function Calls


Using the Compiler

Compiling and Linking Programs
Compiling and Linking Programs
Compiling a Program from a File
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs >
Using the Compiler

VLISP provides several ways to access and use the file compiler. To compile a single AutoLISP file, you can use the vlisp-compile function. To compile many AutoLISP files into a single VLX file, you can use the Make Application wizard. The vlisp-compile function and the Make Application wizard are described in this chapter.

If your application consists of a set of AutoLISP files loaded in parallel, it is recommended that you use the VLISP integrated project management facilities to compile your files. The project manager automatically recompiles files that have changed, allows you to find code segments without knowing which files contain them, and optimizes the use of function calls and local variables in the compiled files. These features are explained in detail in .


Compiling a Program from a File

Using the Compiler
Compiling and Linking Programs
Choosing a Compiler Mode
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs >
Compiling a Program from a File

To compile a single AutoLISP file, call the vlisp-compile function. The function syntax is

(vlisp-compile 'mode “filename” [out-filename])

For this function

  • mode is a symbol identifying the compiler mode
  • filename is a string naming the source file
  • out-filename is a string naming the compiled output file

Topics in this section

  • Choosing a Compiler Mode
  • Identifying the Input File
  • Naming an Output File


Choosing a Compiler Mode

Compiling a Program from a File
Compiling a Program from a File
Identifying the Input File
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs > Compiling a Program from a File >
Choosing a Compiler Mode

The mode parameter indicates the compilation mode, which can be one of the following:

st

Standard build mode

lsm

Optimize and link indirectly

lsa

Optimize and link directly

The standard mode produces the smallest output file and is suitable for programs consisting of a single file.

The optimization options result in more efficient compiled files, which becomes important as your programs grow in size and complexity. The basic functions of optimization are as follows:

  • Link function calls to create direct references to the compiled function in the compiled code, instead of to the function symbol. This feature improves the performance of the compiled code and protects the code against function redefinition at runtime.
  • Drop function names to make the compiled code more secure and to decrease program size and load time.
  • Drop the names of all local variables and directly link their references. This also makes the compiled code more secure and decreases program size and load time.

The VLISP project management feature allows you to tailor the optimization options to the specific needs of your application. See to learn more about choosing optimization options.


Identifying the Input File

Choosing a Compiler Mode
Compiling a Program from a File
Naming an Output File
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs > Compiling a Program from a File >
Identifying the Input File

If your source file is in the AutoCAD support file search path, you do not have to include the path name when specifying the file name. The search path is set by choosing Tools [image] Options from the AutoCAD menu, then clicking the Files tab and selecting Support File Search Path:

For example, if you are compiling the yinyang.lsp program file that is in the AutoCAD Sample\VisualLISP directory, and Support File Search Path is set as indicated in the previous figure, you can issue the following command to compile the program:

(vlisp-compile
'st "yinyang.lsp")

If the AutoCAD sample\visuallisp directory is not in the support file search path, you must include the entire path name when specifying the source file. For example:

(vlisp-compile
'st "c:/program files/ <AutoCAD installation directory>/sample/visuallisp/yinyang.lsp")

If you omit the file extension from a file name, VLISP assumes the .lsp extension.

When specifying the file path name, replace the backslash symbol (\) you normally use for file names with either a forward slash or a double backslash, following the usual AutoCAD convention.


Naming an Output File

Identifying the Input File
Compiling a Program from a File
Walking through a Compile Example
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs > Compiling a Program from a File >
Naming an Output File

The compiler produces code in the fast-load AutoLISP format (FAS). By default, the output file containing this code has the same name as the input file, but with an extension of .fas. You can override the default name by specifying an output file name. For example, to compile yinyang.lsp and produce an output file named GoodKarma.fas, issue the following command:

 (vlisp-compile 'st "yinyang.lsp" "GoodKarma.fas")
NoteIf you specify an output file name but do not specify a path name for either the input or the output file, VLISP places the output file in the AutoCAD default installation directory.

In most instances, you'll want to specify the full path name of the output file. For example:

(vlisp-compile
'st  "yinyang.lsp " "c:/program files/.../sample/visuallisp/goodkarma")

This ensures that the output file is placed in the directory you want..


Walking through a Compile Example

Naming an Output File
Compiling and Linking Programs
Loading and Running Compiled Programs
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs >
Walking through a Compile Example

You can use the yinyang.lsp file in the AutoCAD sample\visuallisp directory to exercise the vlisp-compile function.

To compile the yinyang.lsp sample program

  1. At the Console prompt, enter the following:
    (vlisp-compile
    'st "c:/program
files/ <AutoCAD installation directory>/sample/visuallisp/yinyang.lsp")

    This command requests a standard mode compile of the yinyang.lsp file. No output file name is specified, so the compiled result will be saved in a file named yinyang.fas and will be placed in the same directory as the input file (the AutoCAD sample\visuallisp directory).

  2. Look at the Build Output window displayed after the command executes. If necessary, scroll up in the window to see all the compiler messages. If the compile completed successfully, the window contains messages like the following:

During compilation, the compiler prints function names and various messages about each stage of compilation. The first stage is syntax and lexical checking of the source code. If the compiler encounters errors, it issues messages and halts the compilation process. The compiler issues warnings if it encounters expressions it considers dangerous, such as redefining existing AutoLISP functions or assigning new values to protected symbols. If the compiler displays warning or error messages, you can view and edit the source code that caused these messages by double-clicking on the message in the Build Output window.

If compilation is successful, as in the example contained in the above procedure, the Build Output window displays the name of the compiled output file.


Loading and Running Compiled Programs

Walking through a Compile Example
Compiling and Linking Programs
Loading Extended AutoLISP Functions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs >
Loading and Running Compiled Programs

Compiled AutoLISP programs can be loaded and run from either the VLISP Console window or the AutoCAD Command prompt, or by choosing Tools [image] Load Application from the AutoCAD menu. This is true of both .fas files and .vlx files, which may contain multiple compiled programs. (See Making Application Modules for information on creating .vlx files.)

To run a compiled program from the Visual LISP Console window

  1. Load the program by invoking the load function from the Console prompt. For example, to load the compiled yinyang program created in Walking through a Compile Example, enter the following command:
     (load "c:/program files/<AutoCAD installation
directory> /sample/visuallisp/yinyang.fas")

    If you specify a file name without a path or extension, LOAD looks in the current directory for a matching file name with a .vlx, .fas, or .lsp extension. If LOAD does not find a match, it continues to search the rest of the AutoCAD search path for a matching file name. The search stops in the first directory that contains a matching file name with any of the valid extensions. In that directory, if there are multiple matching files with valid extensions, the file with the most recent timestamp is loaded. If there are multiple files with the same timestamp, the preference order is VLX, FAS, LSP.

    If you specify a path to LOAD but omit the file type, the function looks for VLX, FAS, or LSP files with a matching name in the specified directory, and loads the one with the most recent timestamp.

    If you prefer less typing and more clicking, choose File [image] Load File from the VLISP menu, and use the Load Lisp File dialog box to select the file you want to load. Remember to use the Files of Type pull-down list in this dialog box to specify the type of file you want to load, otherwise VLISP lists only .lsp files in the dialog box. You can select from the following types:

    • Lisp Source Files (.lsp files)
    • Compiled AutoLISP Files (.fas files)
    • VL Packed Application (.vlx files)
    • All files (lists all files in the specified directory)

    Choose Open to load the selected files.

  2. At the VLISP Console prompt, enter the name of the function you want to run, enclosing the name in parentheses. For example:
     (yinyang)

    VLISP transfers control to AutoCAD to display program prompts and accept user input.

Once you load a program, you can run it from either the AutoCAD Command prompt or the VLISP Console window prompt. Note that if the name of the function you are running begins with c:, you can invoke it from the AutoCAD Command prompt as if it were an AutoCAD command, that is, without enclosing the name in parentheses. See for more information on this feature.

Refer to the AutoLISP Reference for more information on the load function.

Topics in this section

  • Loading Extended AutoLISP Functions


Loading Extended AutoLISP Functions

Loading and Running Compiled Programs
Loading and Running Compiled Programs
Linking Function Calls
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs > Loading and Running Compiled Programs >
Loading Extended AutoLISP Functions

VLISP provides some extensions to the AutoLISP language that are not loaded automatically when you start AutoCAD. These functions have names that begin with vla-, vlax-, and vlr-. The vla- functions implement AutoLISP ActiveX® support. The vlax- functions provide ActiveX utility and data conversion functions, dictionary handling functions, and curve measurement functions. The vlr- functions provide support for AutoCAD reactors. Before you can use any of these functions, you must load the AutoLISP extensions with the following function call:

 (vl-load-com)

This function first checks if the AutoLISP extensions are already loaded; if so, the function does nothing, otherwise it loads the extensions.

AutoLISP code that includes calls to vla-, vlax-, or vlr- functions should always begin with a call to vl-load-com to ensure that the code will run; it should not be left up to the user to load the extensions. If your application does not call vl-load-com, the application may fail.


Linking Function Calls

Loading Extended AutoLISP Functions
Compiling and Linking Programs
Making Application Modules
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Compiling and Linking Programs >
Linking Function Calls

The process of compiling function calls results in VLISP creating a loadable module containing in-line copies of some AutoLISP built-in functions. In-line compilation of built-in functions increases the efficiency of the resulting code, but may change the behavior of some tricky AutoLISP programs.

For example, if your program contains an in-line copy of a built-in function, and that function is subsequently redefined, your program does not use the new function definition. A copy of the old definition is part of the program's load module, and that version is called directly. You must recompile your program to pick up the new function definition.

If you include both direct and indirect calls to the same function, your program could end up using different versions for different function calls. This is one reason why combining direct and indirect calls within a single program is not recommended.

When using multiple-file applications in conjunction with direct linking, it is highly recommended that you use the VLISP built-in project management system along with its functions to optimize code automatically. The project management system provides a greater degree of control over compilation and linking of program files than does the vlisp-compile function. See for details.


Making Application Modules

Linking Function Calls
Building Applications
Creating a New Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications >
Making Application Modules

VLISP provides you with the ability to create a single, stand-alone executable module for your application. This module incorporates all your application's compiled files, and can include DCL, DVB, and other files that your application may need. Executable VLISP modules are known as VLX files, and are stored in files named with a .vlx extension.

A Make Application wizard guides you through the application building process in VLISP. The result of this process is a Make file, which is often referred to by its file extension, .prv. The Make file contains all the instructions VLISP needs to build the application executable.

Topics in this section

  • Creating a New Application
  • Loading and Running Visual LISP Applications
  • Changing Application Options
  • Rebuilding an Application
  • Updating an Application


Creating a New Application

Making Application Modules
Making Application Modules
Understanding the Output from Make Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Making Application Modules >
Creating a New Application

It is recommended you build your application only after you have fully debugged it. Compiler errors during the Make process may prevent the application wizard from completing successfully.

There are two modes of the Make Application wizard: simple and expert. In the simple mode, you need only identify the files in your application and name the files you want to create. The expert mode allows for many additional options.

To build an executable file with the Make Application wizard

  1. Choose File [image] Make Application [image] New Application Wizard from the VLISP menu to start the Make Application wizard. VLISP displays a Wizard Mode dialog box asking you to choose the mode you want:

    Select Expert mode, so you can see all the possible Make options; then press the Next button.

  2. VLISP displays the following Application Directory dialog box, where you name your application and specify where you want the application files built by Make Application to reside:

    The Application Directory dialog box appears in both the Simple and Expert Wizard modes.

    You can enter the full path name in the Application Location field, or press the Browse button and identify the output directory (folder) using a standard Windows dialog box.

    The Make Application wizard uses the Application Name when it creates the application executable (.vlx) file and the Make (.prv) file. For example, if you specify an application name of myapp, the Make Application wizard creates files myapp.vlx and myapp.prv.

    If you need to go back to a previous Make Application wizard step and change something, press the Back button. Otherwise, press Next to continue.

  3. The Application Options dialog box is displayed when you run the Make Application wizard in Expert mode. In this dialog box, you choose whether you want your application to run in its own namespace or in the namespace of the document from which the VLX is loaded. See Designing for a Multiple Document Environment for a discussion of namespaces and separate-namespace VLX behavior.

    The ActiveX Support option is available if you choose to run your application in a separate namespace. Selecting this option results in automatic loading of AutoLISP ActiveX support functions when the VLX is loaded.

    Choose Next to continue building the application.

  4. VLISP displays a dialog box in which you specify the LISP files to be loaded when your application loads.

    The LISP Files to Include dialog box appears in both the Simple and Expert Wizard modes.

    You can specify AutoLISP source code files, compiled AutoLISP (FAS) files, or a VLISP project file. Click the pull-down button to choose the type of file you want to include, then press the Add button to display the following dialog box for selecting the files:

    You can select multiple files using the standard Windows file selection methods. After selecting file names, press Open to add the files to your application. To add more files of a different type, choose the file type from the pull-down list and press Add again.

    If you specify AutoLISP source files, VLISP compiles those program files when it builds the application. If you specify a project file, all the project's files are compiled and included in the output module. See for information on creating and using project files.

    To remove files from the application, select the files you no longer want and press the Remove button. You can also select one or more files, right-click, and choose Remove from the shortcut menu.

    VLISP loads the application's files in the order they are listed in the List Files to Include dialog box. You may need to reorder the file list. For example, if you call a function at load time, the function must be defined before it is used. In this case, you want to place the file defining that function first. The List Files to Include dialog box contains buttons you can use to move files around in the list. Select a file name, then choose from among the following buttons:

    • Top Move to the top of the list.
    • Up Move ahead of the file just above in the list.
    • Dn Move behind the file just below in the list.
    • Btm Move to the bottom of the list.

    You can also right-click and choose these actions from a shortcut menu.

    Note that the load order of project files is specified when you define the project. (See of the chapter.)

    When you have finished specifying your application's AutoLISP files, press Next to continue to the next step in the Make Application wizard.

  5. The Resource Files to Include dialog box is displayed when you run the Make Application wizard in Expert mode. If your application includes additional files, such as dialog control language (DCL) files, you can include them in your application's VLX module by selecting them in the dialog box.

    You can specify the following types of resource files:

    • AutoLISP source files
    • Compiled LISP files
    • Visual LISP project files
    • DCL files
    • DVB files
    • Text files

    All program files can be loaded by the VLX. If you choose a Visual LISP project file, all files defined in the project files are compiled and included in the VLX.

    Click the pull-down button to choose the type of files you want to include, then press the Add button to display the dialog box for selecting the files. In the file selection dialog box, you can select multiple files using the standard Windows file selection methods. After selecting file names, press Open to add the files to your application.

    To add more files of a different type, choose the file type from the pull-down list and press Add again.

    To remove resource files from your application, select the files you no longer want and press the Remove button. You can also select one or more files, right-click, and choose Remove from the shortcut menu.

    After selecting resource files for your application, press Next to continue the Make Application process.

  6. The Application Compilation Options dialog box is displayed only in Expert mode. You can select the compilation and linkage options for your application in the dialog box.

    Refer to Choosing a Compiler Mode for information on these options.

    After selecting your compilation options, press Next to continue to the final step of the Make Application process.

  7. For the final step in the Make Application wizard, you can tell VLISP to build your application. The Review Selections/Build Application dialog box appears in both Simple and Expert modes.

    VLISP saves all your application options in a Make (.prv) file. The Make file also includes all the instructions that VLISP needs to build the application. If you do not elect to build the application now, VLISP can use the Make file to build the application later.

    Choose Finish to conclude the Make Application process.

Topics in this section

  • Understanding the Output from Make Application


Understanding the Output from Make Application

Creating a New Application
Creating a New Application
Loading and Running Visual LISP Applicationsbuilding applications:making application modules:loading and running VLISP applications
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Making Application Modules > Creating a New Application >
Understanding the Output from Make Application

VLISP executes instructions in a Make file to build an application. Output messages from this process appear in two VLISP windows: the Build Output window and the Console window. The Build Output window contains messages relating to any compilation of AutoLISP source code into .fas files. In a successful compile, the output looks like the following:

The compiler messages identify the following items:

  • The name and directory path of the source files being compiled.
  • The functions defined in the source file.

    In the above example, four functions are identified: GP:GETPOINTINPUT, GP:GETDIALOGINPUT, GP:DRAWOUTLINE, and C:GPATH.

  • The name and path of the output .fas files.

The VLISP Console window displays messages relating to the creation of the application executable, the .vlx file. If the Make Application process succeeds, the Console window displays the path and file name of the .vlx, as in the following example:


Loading and Running Visual LISP Applications

Understanding the Output from Make Application
Making Application Modules
Changing Application Options
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Making Application Modules >
Loading and Running Visual LISP Applications

To execute the functions in a VLX application, you must first load the VLX file using any of the following methods:

  • Call the AutoLISP load function.
  • Choose File [image] Load File from the VLISP menu.
  • Choose Tools [image] Load Application from the AutoCAD menu.

See Loading and Running Compiled Programs for specific instructions on loading and running application functions.


Changing Application Options

Loading and Running Visual LISP Applicationsbuilding applications:making application modules:loading and running VLISP applications
Making Application Modules
Rebuilding an Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Making Application Modules >
Changing Application Options

VLISP allows you to change the way your application is designed. For example, you can change compilation options, or add or remove AutoLISP files from the application.

To change an application's definition

  1. Choose File [image] Make Application [image] Existing Application Properties. VLISP displays a dialog box for you to specify your application's Make (.prv) file, which is where VLISP stores the application's properties.
  2. Specify the name of your application's Make file, then press Open. VLISP displays the Application Properties dialog box.
  3. Click the tab of the property you want to change.
  4. After changing a property, press Apply to save the change, or press OK to save the change and exit the Application Properties dialog box.

Load/Compile Options

Compile AutoLISP source files using the Standard compile option, or Optimize and Link the files.

Tune Directories

Identify LISP Object directory and Target directory. The Object directory is where VLISP places .fas and temporary files created by the compiler. Target directory is another name for “Application directory,” which is where Make Application stores the VLX file. If a field identifying a directory is blank, VLISP uses the .prv directory.

Application Options

Create a separate-namespace VLX and include ActiveX support. If ActiveX Support is selected along with Separate Namespace, loading the VLX will automatically result in the loading of AutoLISP ActiveX support functions.

Load Files

AutoLISP source files included in the application.

Resource Files

Additional resource files included in the application.


Rebuilding an Application

Changing Application Options
Making Application Modules
Updating an Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Making Application Modules >
Rebuilding an Application

After changing application options or modifying source code, you need to rebuild your application for the changes to take effect.

To rebuild an application

  1. Choose File [image] Make Application [image] Rebuild Application from the VLISP menu.
  2. Specify the location of your application's Make file.
  3. Choose Open to rebuild the application.

In rebuilding the application, VLISP recompiles all .lsp source files, applying the specified compilation options, and packages your application files into a new .vlx file. If your application contains many AutoLISP files, and you have only changed the source code in one or two files, the Make Application option can rebuild your application more efficiently. See the following section for information on using this option.


Updating an Application

Rebuilding an Application
Making Application Modules
Designing for a Multiple Document Environment
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Making Application Modules >
Updating an Application

If you change just a small piece of your application's AutoLISP source code, you can have VLISP rebuild your application VLX while compiling only those files you've updated. To make this type of update, choose File [image] Make Application [image] Make Application from the VLISP menu, and select your application's Make file. VLISP rebuilds the application based on the information contained in the Make file, and automatically compiles any application source files for which either of the following is true:

  • There is no compiled (.fas) version of the file.
  • There is a compiled version of the file, but the source file has been modified since that compile (that is, the date of the source file is more current than the date of the .fas file).

Note that if you change application options (for example, from Standard compile mode to Optimize and Link), you must use the Rebuild Application menu option to create a new VLX with the changes you specified. The Make Application command only checks for changes to AutoLISP source code files, not to application options.


Designing for a Multiple Document Environment

Updating an Application
Building Applications
Understanding Namespaces
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications >
Designing for a Multiple Document Environment

Using the AutoCAD multiple document interface (MDI), users can copy objects between drawings and display several drawings side by side in a single work session. When you design an AutoCAD application, you need to understand how open drawing documents relate to one another.

Topics in this section

  • Understanding Namespaces
  • Running an Application in Its Own Namespace
  • Sharing Data Between Namespaces
  • Handling Errors in an MDI Environment
  • Limitations on Using AutoLISP in an MDI Environment


Understanding Namespaces

Designing for a Multiple Document Environment
Designing for a Multiple Document Environment
Running an Application in Its Own Namespace
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment >
Understanding Namespaces

The concept of namespaces was introduced to prevent applications running in one drawing window from unintentionally affecting applications running in other windows. A namespace is a LISP environment containing a set of symbols (for example, variables and functions). Each open AutoCAD drawing document has its own namespace. Variables and functions defined in one document namespace are isolated from variables and functions defined in other namespaces.

You can see how this works by trying a simple example.

To see the effect of multiple namespaces

  1. Open two new drawings in AutoCAD.
  2. Choose Window [image] Tile Vertically from the AutoCAD menu. You should see two open document windows side by side within the main AutoCAD window:

    The document's title bar indicates which window is currently active. In the preceding example, Drawing1.dwg is the current document.

  3. Enter the following at the Command prompt:
     (setq draw1foo "I am drawing 1")

    This sets the draw1foo variable to a string.

  4. Activate Drawing2.dwg (click in the window's title bar).
  5. See if draw1foo contains the value you just set for it:
    Command: !draw1foo
    nil

    The variable is nil because it has not been set in this document's namespace; you set it in the namespace belonging to Drawing1.dwg.

  6. Enter the following at the Command prompt:
     (setq draw2foo "I too am a drawing, but number 2")

    This sets the draw2foo variable to a string.

  7. Activate Drawing1.dwg.
  8. Test the values of variables draw1foo and draw2foo:
    Command: !draw1foo
    "I am drawing 1"
    Command: !draw2foo
    nil

    The draw1foo variable contains the value you set for it, but draw2foo is nil because you did not set it to a value in the current namespace; you set a different variable of the same name in Drawing2.dwg's namespace.

VLISP provides ways for you to share variables between namespaces, but you must take explicit action to do so. (See Sharing Data Between Namespaces.)

Like variables, functions defined in an AutoLISP file are known only to the document that was active when the file was loaded. The functions in the file are loaded in the current document's namespace and are known only to that document.

To see how functions are affected by multiple namespaces

  1. Load a LISP file from either the AutoCAD Command prompt or the VLISP Console prompt. For example:
    (load "yinyang.lsp")
  2. Invoke the function.
  3. Open a second drawing window.
  4. With the second drawing window active, try invoking the function again. The response will be an error message saying the function is not defined.

You can use the vl-load-all function to load the contents of an AutoLISP file into all AutoCAD drawing documents. For example, the following command causes the contents of the yinyang.lsp file to be loaded into all open documents, and into any documents opened later in the AutoCAD session:

(vl-load-all "yinyang.lsp")

The vl-load-all function is useful for testing new functions in multiple documents, but in general you should use acaddoc.lsp to load files that are needed in every AutoCAD document.


Running an Application in Its Own Namespace

Understanding Namespaces
Designing for a Multiple Document Environment
Accessing External ObjectARX Functions from a Separate-Namespace VLX
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment >
Running an Application in Its Own Namespace

You can define a namespace for a VLX application in VLISP. A VLX application defined in this manner is referred to as a separate-namespace VLX. When you load a separate-namespace VLX, it runs in its own namespace, not the namespace of the document from where you loaded the VLX. The option to define a VLX application with its own namespace is part of the Make Application procedure (see Making Application Modules).

If you try to load a separate-namespace VLX that is already loaded, you'll receive an error indicating this. Use the vl-unload-vlx function to unload the application. The function's syntax is

 (vl-unload-vlx“appname” )

For appname, specify the file name of the VLX, without the path or the .vlx extension.

Variables and functions defined in a VLX application's namespace are known only to the application, not to the drawing document that was active when the application was loaded. This allows you to protect your variables from accidentally—or intentionally—being overwritten by other applications or users.

A VLX application can export function names to a document namespace to enable those functions to be accessed within the context of that document. The following diagram illustrates how this works:

The diagram shows an AutoCAD session containing two open drawing documents. A VLX application named “hangman” is loaded with respect to Document1 (for example, a user opened Document1 and then loaded the VLX application from the AutoCAD Command prompt). The hangman application established its own namespace and declared the bar function and the dooley variable in that namespace. The VLX exported the bar function to Document1's namespace. When a user invokes bar from Document1, bar runs in the application's namespace. The bar function is unknown to Document2, and neither document has access to the dooley variable (because the VLX did not export it). You can load another instance of the hangman VLX into Document2, but this instance will have its own namespace and its own copies of bar and dooley.

NoteWhen you load a VLX file that has not been defined as having its own namespace, the environment is similar to that of a loaded file. All functions and variables defined in the VLX are loaded in the document's namespace.

Topics in this section

  • Accessing External ObjectARX Functions from a Separate-Namespace VLX
  • Making Functions Available to Documents
  • Making Separate-Namespace Functions Available to Other VLX Applications
  • Referencing Variables in Document Namespaces


Accessing External ObjectARX Functions from a Separate-Namespace VLX

Running an Application in Its Own Namespace
Running an Application in Its Own Namespace
Making Functions Available to Documents
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment > Running an Application in Its Own Namespace >
Accessing External ObjectARX Functions from a Separate-Namespace VLX

In order to access functions that are defined in an external ObjectARX application from a separate-namespace VLX, you must first issue vl-arx-import to import the function. ObjectARX functions are identified as data type EXRXSUBR. For example, the following command identifies startapp as an external ObjectARX function:

Command: (type startapp)

EXRXSUBR

The following function works correctly if loaded from an LSP file:

(vl-doc-export 'StartApp2)
(vl-load-com)
(defun StartApp2 ()
   (setq acadApp (vlax-get-acad-object))
   (setq acadDoc (vla-Get-ActiveDocument acadApp))
   (setq acadPrefs (vla-Get-Preferences acadApp))
   (setq acadPrefFiles (vla-get-Files acadPrefs))
   (setq hlpFile (vla-Get-HelpFilePath acadPrefFiles))
   (startapp "winhlp32" hlpFile)
   (princ)
)
(princ "\nStartApp2 is loaded, Type (StartApp2) to Run.")
(princ)
However, if you compile StartApp2
as a separate-namespace VLX and try to run the function, it fails
with the following error message:
"no function definition:
STARTAPP"
To correct this, import startapp using
the vl-arx-import function,
as shown in the following revised code:
(vl-doc-export 'StartApp2)
(vl-load-com)
(vl-arx-import 'startapp)
(defun StartApp2 ()
   (setq acadApp (vlax-get-acad-object))


Making Functions Available to Documents

Accessing External ObjectARX Functions from a Separate-Namespace VLX
Running an Application in Its Own Namespace
Making Separate-Namespace Functions Available to Other VLX Applications
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment > Running an Application in Its Own Namespace >
Making Functions Available to Documents

By default, functions defined in a separate-namespace VLX are not exposed to the document namespace from which the VLX is loaded. You must use the vl-doc-export function to expose functions to document namespaces. When issued from a VLX that runs in its own namespace, vl-doc-export exposes the specified function to any document namespace that loads the VLX. The vl-doc-export function accepts a single argument, a symbol identifying the function name. For example, look at the following code:

(vl-doc-export 'kertrats)
(defun kertrats ()
  (princ "This function goes nowhere")
)

This example defines the kertrats function, which simply prints a message. The defun for the function is preceded by a vl-doc-export call that causes the function to be exported to the document namespace.

To see how vl-doc-export works in a separate-namespace VLX

  1. In a VLISP text editor window, copy the following code into a file:
    (defun kertrats ()
      (princ "This function goes nowhere")
    )

    Note that this code does not contain a call to vl-doc-export.

  2. Save the file you just created.
  3. Use the VLISP Make Application wizard to build a VLX from your program file. Specify the following wizard options:
    • Wizard mode: Expert
    • Application name: doctest
    • Application options: Separate-namespace
    • Compilation options: Optimize
  4. From either the AutoCAD Command prompt or the VLISP Console window prompt, load the doctest VLX file.
  5. Try running the kertrats function.

    You should receive an error message indicating the function is not defined.

  6. Add the following line of code to the beginning of your program file:
    (vl-doc-export 'kertrats)
  7. Save the file, then rebuild the application.
  8. Use vl-unload-vlx to unload the VLX, then load and run the VLX again. This time, kertrats should run successfully.

You can issue a vl-doc-export call outside the context of a separate-namespace VLX application, but it has no effect.

The vl-list-loaded-vlx function returns a list of all separate-namespace applications associated with the current document. For example:

_$ (vl-list-loaded-vlx)
(DOCTEST)

To determine what functions have been exported from a separate-namespace application into the current document, use vl-list-exported-functions. When calling this function, you must pass it a string naming the application you are checking. For example, the following command returns a list of the functions exported by the doctest application:

_$ (vl-list-exported-functions "doctest")
("KERTRATS")

The results show that a single function, kertrats, was exported from doctest to the current document's namespace.

NoteCurrently, if separate namespace VLX A associated with document A loads separate namespace VLX B, then all of VLX B's exported functions are automatically defined in document A. Note also that VLX B's exported functions are not defined in VLX A until VLX A issues an explicit import. (See Making Separate-Namespace Functions Available to Other VLX Applications.)


Making Separate-Namespace Functions Available to Other VLX Applications

Making Functions Available to Documents
Running an Application in Its Own Namespace
Referencing Variables in Document Namespaces
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment > Running an Application in Its Own Namespace >
Making Separate-Namespace Functions Available to Other VLX Applications

Functions defined in one separate-namespace VLX are not exposed to any other separate-namespace VLX applications. If a function has been exported through vl-doc-export, you can use the vl-doc-import function to make the function available to another separate-namespace VLX.


Referencing Variables in Document Namespaces

Making Separate-Namespace Functions Available to Other VLX Applications
Running an Application in Its Own Namespace
Sharing Data Between Namespaces
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment > Running an Application in Its Own Namespace >
Referencing Variables in Document Namespaces

Variables defined in a separate-namespace VLX are not known to the document namespace associated with the VLX. However, a separate-namespace VLX can access variables defined in a document namespace using the vl-doc-ref and vl-doc-set functions.

The vl-doc-ref function copies the value of a variable from a document namespace. The function requires a single argument, a symbol identifying the variable to be copied. For example, the following function call copies the value of a variable named aruhu:

(vl-doc-ref 'aruhu)

If executed within a document namespace, vl-doc-ref is equivalent to the eval function.

The vl-doc-set function sets the value of a variable in a document namespace. The function requires two arguments: a symbol identifying the variable to be set, and the value to set for the variable. For example, the following function call sets the value of a variable named ulus:

(vl-doc-set 'ulus "Go boldly to noone")

If executed within a document namespace, vl-doc-set is equivalent to the setq function.

To set the value of a variable in all open document namespaces, use the vl-propagate function. For example, the following function calls set a variable named fooyall in all open document namespaces:

(setq fooyall "Go boldly and carry a soft stick")
(vl-propagate 'fooyall)

This command not only copies the value of fooyall into all currently open document namespaces, but also causes fooyall to automatically be copied to the namespace of any new drawings opened during the current AutoCAD session.


Sharing Data Between Namespaces

Referencing Variables in Document Namespaces
Designing for a Multiple Document Environment
Handling Errors in an MDI Environment
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment >
Sharing Data Between Namespaces

VLISP provides a blackboard namespace for communicating the values of variables between namespaces. The blackboard is a namespace that is not attached to any document or VLX application. You can set and reference variables in the blackboard from any document or VLX. Use the vl-bb-set function to set a variable, and use vl-bb-ref to retrieve a variable's value.

For example, the following command sets the foobar blackboard variable to a string:

Command: (vl-bb-set 'foobar "Root toot toot")
"Root toot toot"

The vl-bb-ref function returns the specified string. The following example uses vl-bb-ref to retrieve the value of foobar from the blackboard:

Command: (vl-bb-ref 'foobar)
"Root toot toot"

Note that these functions require you to pass a symbol naming the variable you are referencing ('var-name), not the variable name (var-name).

Setting or retrieving variable values in the blackboard namespace has no effect on variables of the same name in any other namespace.

To demonstrate that document variables are unaffected by blackboard variables

  1. From the VLISP Console window (or the AutoCAD Command prompt), use vl-bb-set to set the *example* blackboard variable.
    _$ (vl-bb-set '*example* 0)
    0

    The *example* variable is set to 0 in the blackboard namespace.

  2. Use vl-bb-ref to verify the value of the variable you set in the previous step.
    _$ (vl-bb-ref '*example*)
    0
  3. See what value *example* has in the current AutoCAD document.
    _$ *example*
    nil

    The *example* variable is nil because it has not been set in the document namespace.

  4. Set *example* in the current document.
    _$ (setq *example* -1)
    -1

    The *example* variable is set to -1 in the document namespace.

  5. Check the current value of *example* in the blackboard.
    _$ (vl-bb-ref '*example*)
    0

    The blackboard variable named *example* is still set to the value assigned in step 1; setting the document variable of the same name in step 4 had no effect on the blackboard.

VLISP also provides the vl-doc-set and vl-doc-ref functions to set and retrieve document namespace variables from a separate-namespace VLX, and vl-propagate to set the value of a variable in all open document namespaces. These functions are described in Referencing Variables in Document Namespaces.


Handling Errors in an MDI Environment

Sharing Data Between Namespaces
Designing for a Multiple Document Environment
Handling Errors in a VLX Application Running in Its Own Namespace
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment >
Handling Errors in an MDI Environment

By default, each document namespace is provided with its own *error* function, which is defined as follows:

(defun *error* (msg)
               (princ "error: ")
               (princ msg)
               (princ)
)

A VLX application running within a document namespace shares the default error-handler function. You may want to add error-handling logic to your application.

Topics in this section

  • Handling Errors in a VLX Application Running in Its Own Namespace


Handling Errors in a VLX Application Running in Its Own Namespace

Handling Errors in an MDI Environment
Handling Errors in an MDI Environment
Limitations on Using AutoLISP in an MDI Environment
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment > Handling Errors in an MDI Environment >
Handling Errors in a VLX Application Running in Its Own Namespace

For VLX applications executing within their own namespace, you can either use the default error function or you can define an error handler specifically for the application.

If you define an error handler for a VLX running in its own namespace, you can call the vl-exit-with-error function to pass control from the VLX error handler to the document namespace's *error* function. The following example uses vl-exit-with-error to pass a string to the document's *error* function:

(defun *error* (msg)
  ... ; processing in VLX namespace/execution context
(vl-exit-with-error (strcat "My application bombed! " msg)))

A VLX *error* handler can use the vl-exit-with-value function to return a value to the document namespace from which the VLX was invoked. The following example uses vl-exit-with-value to return the integer value 3 to the program that called the VLX from the document namespace:

(defun *error* (msg)
  ... ; processing in VLX-T namespace/execution context
  (vl-exit-with-value  3))
(vl-doc-export 'foo)
(defun foo (x)
  (bar x)
  (print 3))
(defun bar (x) (list (/ 2 x) x))

Any instructions pending at the time the error occurred are flushed.

If your VLX namespace error handler does not use either vl-exit-with-error or vl-exit-with-value, then control returns to the command prompt after execution of the error handler. You can only call vl-exit-with-error and vl-exit-with-value in the context of a VLX application's error handler; it is an error to invoke these functions in any other situation.


Limitations on Using AutoLISP in an MDI Environment

Handling Errors in a VLX Application Running in Its Own Namespace
Designing for a Multiple Document Environment
Maintaining Visual LISP Applications
AutoLISP Developer's Guide > Using the Visual LISP Environment > Building Applications > Designing for a Multiple Document Environment >
Limitations on Using AutoLISP in an MDI Environment

When using native AutoLISP in an MDI environment, you can only work with one drawing document at a time. Although AutoLISP provides support for exchanging variables and exposing functions to multiple namespaces, you cannot, for example, run a function in one document namespace and issue entmake to create an entity in another document namespace. AutoLISP does not support accessing information across multiple drawings.

You can access multiple document namespaces using ActiveX automation, and AutoLISP provides access to ActiveX methods (see ). However, accessing multiple documents with ActiveX is an unsupported feature of AutoLISP. For example, an AutoLISP program running in the context of document A can change the active document to document B by calling vla-put-activedocument. Changing the active document, though, immediately suspends execution of the program. The program may resume execution if the user activates the window containing document A but the system will be in an unstable state and likely to fail.

WarningIf you do use ActiveX to work in MDI, be aware that if you close all AutoCAD drawings you lose access to AutoLISP and will cause an exception.


Maintaining Visual LISP Applications

Limitations on Using AutoLISP in an MDI Environment
Using the Visual LISP Environment
Managing Multiple LISP Files
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Maintaining Visual LISP Applications

You can maintain large programs by creating a Visual LISP project and optimizing code.

This chapter describes how you can maintain large applications containing multiple files by defining the application as a Visual LISP® project. Aside from defining the components in your application, you can use VLISP projects to define compiler options for the application. This chapter describes the various compiler options and the consequences of each, and tells you how to override these options for individual files in a project.

Topics in this section

  • Managing Multiple LISP Files
  • Defining a Project
  • Working with Existing Projects
  • Optimizing Application Code


Managing Multiple LISP Files

Maintaining Visual LISP Applications
Maintaining Visual LISP Applications
Understanding Visual LISP Projects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications >
Managing Multiple LISP Files

Many program examples you have seen in this document have been small, stand-alone AutoLISP® files. Typical AutoLISP applications, however, consist of larger files with many lines of code. An application may include many source code files. After compiling the programs in such an application, you also have a number of FAS files to track.

As the number of application files grows, it becomes more difficult to maintain an application. Determining when you need to recompile files after source code changes can be a challenge. VLISP provides functions that greatly simplify the process of managing multiple-file applications.

Topics in this section

  • Understanding Visual LISP Projects


Understanding Visual LISP Projects

Managing Multiple LISP Files
Managing Multiple LISP Files
LISP, FAS, and Other File Types
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Managing Multiple LISP Files >
Understanding Visual LISP Projects

To aid you in the process of maintaining multiple-file applications, VLISP provides a construct called a project. A VLISP project contains a list of AutoLISP source files, and a set of rules on how to compile the files. Using the project definition, VLISP can do the following:

  • Check which .lsp files in your application have changed, and automatically recompile only the modified files. This procedure is known as a Make procedure.
  • Simplify access to source files by listing all source files associated with a project, making them accessible with a single-click.
  • Help you find code fragments by searching for strings when you do not know which source files contain the text you're looking for. VLISP limits the search to files included in your project.
  • Optimize compiled code by directly linking the corresponding parts of multiple source files.

Before discussing how to define and use VLISP projects, it may help to introduce file types used in VLISP.

Topics in this section

  • LISP, FAS, and Other File Types


LISP, FAS, and Other File Types

Understanding Visual LISP Projects
Understanding Visual LISP Projects
Defining a Project
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Managing Multiple LISP Files > Understanding Visual LISP Projects >
LISP, FAS, and Other File Types

The basic file type in VLISP is the AutoLISP source file. Typically, AutoLISP source files are named with an .lsp file extension. You have seen .lsp files used frequently in previous chapters.

The FAS (.fas) file type was introduced in the previous chapter, Building Applications FAS files are compiled AutoLISP files. These files load faster than AutoLISP source files and are more secure because their contents are not intelligible to users.

Here is a brief summary of the types of files used by the VLISP project management feature:

Visual LISP project file types
File ext. | Type of file | Function
.fas | Compiled AutoLISP code | Compiled AutoLISP programs. May be loaded and run, or compiled into VLX modules
.lsp | AutoLISP source code | Program source files
.ob | Object code | Used internally by VLISP, these files contain compiled AutoLISP code used in building FAS files
.pdb | Project database | Used internally by VLISP, these files contain symbol information used by the compiler
.prj | Project definition | Contains the location and names of all source files that build the project, as well as certain parameters and rules on how to create the final FAS files

In addition to the files recognized by the project manager, VLISP either creates, processes, or recognizes a number of additional types of files, as summarized below:

Additional Visual LISP file types
File ext. | Type of file | Function
.dsk | Desktop save | Contains VLISP environment and window settings. (Note: Editing this file may permanently change the VLISP environment. Do not edit this file without creating a backup copy first.)
._xx | Backup files | Backup copies of edited files, maintained by the VLISP editor. Backup files contain the same name as the original, except that the file extension begins with the underline character (_) and is followed by the first two characters of the original file's extension. For example, the backup file of a LSP file has an ._LS extension; the backup of a DCL file has a ._DC extension.
.vlx | Stand-alone applications | Stand-alone AutoCAD applications, which can be created using the VLISP Make Application wizard.
.c, .cpp, .cch, .hpp, .hh | Language source files | Contain program source code. The VLISP editor recognizes the syntax of these files and color-codes reserved words, strings, and numbers.
.dcl | Dialog control language | Contains definitions of AutoCAD dialog boxes. VLISP can preview these files, and you can include them in Visual LISP executable (VLX) files.
.prv | Make application | Defines the files and options used to build a VLX application with the VLISP Make Application wizard.
.sql | Structured query language | Contains SQL statements. The VLISP text editor recognizes this file type and color-codes the text according to SQL syntax rules.


Defining a Project

LISP, FAS, and Other File Types
Maintaining Visual LISP Applications
Assigning Project Properties
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications >
Defining a Project

To demonstrate the use of projects in VLISP, you can use the sample programs supplied with the AutoLISP Tutorial. This code is available on the AutoCAD® installation CD, but the tutorial files are only included in your installation if you choose a Full install, or if you choose Custom install and select the Tutorials item. If you have already installed AutoCAD and did not install the samples, you can rerun the installation, choose Custom, and select only the Tutorials item.

The sample files used in this chapter are in the Tutorial\VisualLISP\Lesson5 folder of the AutoCAD default installation directory. The files are

  • Gpmain.lsp
  • Gpdraw.lsp
  • Gp-io.lsp
  • Utils.lsp

To create a VLISP project, choose Project [image] New Project from the VLISP menu. VLISP displays a standard Windows dialog box for you to specify a file path and name. For the example in this chapter, the project name is Tutorial. VLISP assigns a .prj extension to the project file name.

Topics in this section

  • Assigning Project Properties
  • Using the Project Window to Work with Project Files


Assigning Project Properties

Defining a Project
Defining a Project
Selecting the Files to Include in a Project
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project >
Assigning Project Properties

The Project Properties dialog box is displayed after you specify a project file name.

Topics in this section

  • Selecting the Files to Include in a Project
  • Identifying the Path Name of Project Files
  • Changing the Order in Which Visual LISP Loads Files
  • Choosing Compiler Build Options


Selecting the Files to Include in a Project

Assigning Project Properties
Assigning Project Properties
Identifying the Path Name of Project Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Assigning Project Properties >
Selecting the Files to Include in a Project

There are two tabs in the Project Properties dialog box. In the Project Files tab, you specify the AutoLISP source files for the project.

The project's home directory is identified just below the tabs. This is where the project file (tutorial.prj) resides. In this example, the home directory is c:\My Documents\VisualLISP\Examples. That's not the directory containing the tutorial sample files, though. To identify the source directory, press the [...] button.

Use the Browse for Folder dialog box to identify the location of the project source files. If you select the Lesson5 directory, the Project Properties dialog box looks like the following:

VLISP lists all files in the directory having an .lsp extension (but does not display the extension in the list). The window is designed so that, by default, you can select multiple file names by just choosing each name. You do not have to press and hold CTRL to select more than one file. To clear a selected name, just choose it again.

To include all the listed files in your project, press the button labeled “(Un)Select all,” then choose the right arrow button. VLISP moves the file names to the window on the right:

To remove a file from the project, select the file's name in the right window and click the left arrow button.


Identifying the Path Name of Project Files

Selecting the Files to Include in a Project
Assigning Project Properties
Changing the Order in Which Visual LISP Loads Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Assigning Project Properties >
Identifying the Path Name of Project Files

The list of included files does not identify the path name of each file (nor does the Look In field; this just identifies the path of the files listed in the left window). Because you can include files from multiple directories in your project, you need to be able to identify the path name of each file. You can do this by highlighting one or more file names and right-clicking to display a shortcut menu:

To display the full path name and the size (in bytes) of source files in the project, choose Log Filenames and Size from the shortcut menu. The information appears in a small, scrollable window near the bottom of the Project Properties dialog box:

If a file is in the Home directory shown in the Project Properties dialog box, VLISP does not spell out its path name. Use the scroll bar to see information about all the files in the project.

Note that you cannot include two files of the same name in a project, even if they are in different directory paths.


Changing the Order in Which Visual LISP Loads Files

Identifying the Path Name of Project Files
Assigning Project Properties
Choosing Compiler Build Options
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Assigning Project Properties >
Changing the Order in Which Visual LISP Loads Files

The shortcut menu for the list of included files also provides commands to move files up and down in the list, and to sort the list by file name or by full path name. VLISP loads the project's files in the order in which they are listed. Sometimes the load order is important. For example, you might have an initialization file that defines global variables needed by all the other program files, and thus must be loaded first. You could select that file name and choose Move to Top to place it first in the project's file list.

You can also use buttons in the Project Properties dialog box to move files around in the list: Top (move to top), Up (move up), Dn (move down), and Btm (move to bottom).

For the tutorial project, the gpmain.lsp file should be loaded last. It contains the following instructions at the end of the file:

(princ "\nType GPATH to draw a garden path.")
(princ)

This results in a prompt telling users how to invoke the application. If VLISP loads gpmain.lsp last, these instructions will display at the AutoCAD Command prompt.

After you move any needed files, press the Apply button.


Choosing Compiler Build Options

Changing the Order in Which Visual LISP Loads Files
Assigning Project Properties
Using the Project Window to Work with Project Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Assigning Project Properties >
Choosing Compiler Build Options

The Build Options tab displays a dialog box in which you can specify compiler options to VLISP. This topic is covered in the Choosing a Compilation Mode section later in this chapter. For now, choose OK to close the Project Properties dialog box.


Using the Project Window to Work with Project Files

Choosing Compiler Build Options
Defining a Project
Selecting Multiple Project Members
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project >
Using the Project Window to Work with Project Files

When you open a VLISP project, VLISP displays a window listing the files in the project:

By default, VLISP lists the project members in the order in which they will be loaded (as defined in the Project Properties dialog box). You can change this order by choosing Arrange Files from the shortcut menu for this window.

The project name appears in the window title bar. Below the title bar are five icons. Each icon is a button that performs a function. The buttons and their functions are as follows:

Project Properties

Displays the Project Properties dialog box for the project. This allows you to view the full path name of each file in the project, add, remove, and reorder project files, and view and change project compiler options.

Load Project FAS

Loads all compiled (.fas) files for the project.

Load Source Files

Loads all the project source files, making them available to be run.

Build Project FAS

Compiles all project source files that have been modified since their last compile.

Rebuild Project FAS

Recompiles all project source files, whether or not they have changed since their last compile.

If you right-click within the file list of the Project Properties dialog box, VLISP displays a shortcut menu. Many of the functions available from the project shortcut menu can also be accomplished in other ways. For example, you've already seen how to add files to projects and remove files from projects. Choosing Remove File from the shortcut menu is a quick way of removing a file from a project, while choosing Add File merely brings you to the Project Properties dialog box.

The following summarizes the commands on the shortcut menu:

Edit

Edits the source code of the selected project members.

Add File

Opens the Project Properties dialog box to add files to the project.

Remove File

Removes the selected members from the project.

Load

Loads the FAS file for the selected project members. If no FAS file exists for a member, loads the AutoLISP source file.

Load Source

Loads the .lsp file for the selected project members.

Check Syntax

Checks AutoLISP syntax of the source code for the selected members.

Touch

Indicates that the selected source files have been updated, but makes no change to the files. This causes VLISP to recompile these programs the next time you ask to compile all changed project files.

Arrange Files

Sorts the project member list, according to one of the available suboptions (load order, name, type, or date).

Multiple Selection

Tells VLISP whether or not to allow selection of multiple members from the list in the Project Properties dialog box. If this option is selected, multiple selection is allowed.

[Un]Select All

Selects all members of the project list, if none is currently selected. If any members are currently selected, this command cancels their selection.

Close Project

Closes the project.

Save Project As

Saves the project.

Topics in this section

  • Selecting Multiple Project Members
  • Loading Project Files
  • Compiling and Recompiling Project Files
  • Editing Project Files
  • Saving and Closing the Project


Selecting Multiple Project Members

Using the Project Window to Work with Project Files
Using the Project Window to Work with Project Files
Loading Project Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Using the Project Window to Work with Project Files >
Selecting Multiple Project Members

The Multiple Selector menu item is available only from the Project Properties dialog box shortcut menu. Choosing this option allows you to select multiple members from the list in the Project window. If the option is selected, a check mark appears next to the Multiple Selector item on the menu. Click on the menu item to toggle it on and off.

If Multiple Selector is in effect, clicking a member name in the Project Properties dialog box acts as a toggle to select or deselect the member. For example, none of the members listed in the following window is selected:

If you click on the name GP-IO, then click on the name GPDRAW, both are selected.

This is unlike the default Windows behavior, where selecting the second list item cancels the first item's selection, unless you press CTRL while selecting the item.

You can also use the Project Properties dialog box shortcut menu to select all members of the project or cancel selection of all members. If no members are currently selected, right-click and choose [Un]Select All to select all the members. If any or all members are already selected, [Un]Select All cancels all selections.


Loading Project Files

Selecting Multiple Project Members
Using the Project Window to Work with Project Files
Compiling and Recompiling Project Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Using the Project Window to Work with Project Files >
Loading Project Files

To load the project's compiled program files, click the Load Project FAS button. This allows you to run the application. If VLISP detects that some of the source files do not exist in compiled format, it displays a message and asks if you want to compile those files:

If you choose Yes, VLISP attempts to compile all .lsp files that do not have a corresponding .fas file. If you choose No, VLISP loads all FAS files it finds for the project, and loads the AutoLISP source for the remaining project files. Choose Cancel to abort the load operation.

To load all project source files instead of their compiled versions, click the Load Source Files button. Remember that debugging breakpoints may be saved within source code files but are removed from the compiled version of the code. You might want to load source files to debug changes you've made to your programs.

Using the Project Properties dialog box shortcut menu, you can choose to load just selected files. Select the files you want to load, and then right-click and choose Load to load the FAS files, or choose Load Source to load the source code. Note that if you choose Load and a FAS file does not exist for a selected file, VLISP loads the AutoLISP source file instead.

NoteThe Lesson5 example from the AutoLISP Tutorial requires a DCL file to run successfully. The DCL file is included in the Lesson5 folder, but you cannot define a DCL file as part of a VLISP project. To run this example successfully, you must copy the DCL file to a directory in the AutoCAD support file search path. You can also define the DCL file as an application component, using the VLISP Make Application wizard. Using this method, the file does not have to be in the AutoCAD search path. Including a Project in a Visual LISP Application demonstrates how to define an application composed of a VLISP project and supporting files, such as DCL files.


Compiling and Recompiling Project Files

Loading Project Files
Using the Project Window to Work with Project Files
Editing Project Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Using the Project Window to Work with Project Files >
Compiling and Recompiling Project Files

One key advantage in defining VLISP projects for your applications is that it provides an efficient method of updating compiled code. You can elect to have VLISP recompile all source files that have changed since the last time they were compiled. By choosing this option, you ensure all FAS files in your application correspond to the latest versions of the program source code. At the same time, you save time by avoiding unnecessary compiles. To invoke this feature, click the Build Project FAS button in the Project Properties dialog box.

You can also choose to recompile all the programs in your project, whether or not they have changed. Click the Rebuild Project FAS button to enable this feature.


Editing Project Files

Compiling and Recompiling Project Files
Using the Project Window to Work with Project Files
Saving and Closing the Projectclosing:projects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Using the Project Window to Work with Project Files >
Editing Project Files

To edit the source file of a project member, select the member from the list in the Project window, then right-click and choose Edit. If the Multiple Selector option is on, you can select multiple members, and VLISP will open a text editor window for each.

NoteIf the Multiple Selector option is not turned on, you can simply double-click a member name to edit it.


Saving and Closing the Project

Editing Project Files
Using the Project Window to Work with Project Files
Working with Existing Projects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Defining a Project > Using the Project Window to Work with Project Files >
Saving and Closing the Project

To save the project properties you defined or modified, right-click in the Project window and choose Save Project As from the shortcut menu. VLISP displays a list of project files. You can either select the name of the current project file to update its contents, or enter a new file name to save the changes as a new project.

When you are finished working with a project, right-click in the Project window and choose Close Project. Note that this only closes the .prj file; any project files that are open in VLISP editor windows remain open.

NoteIf you close the Project Properties dialog box by clicking the Close button, this does not close the project itself. The Project is still open, and you can reopen a Project window for it by choosing it from the Project menu, as described in the next section, Opening a Project


Working with Existing Projects

Saving and Closing the Projectclosing:projects
Maintaining Visual LISP Applications
Opening a Project
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications >
Working with Existing Projects

Some VLISP features described in previous chapters have special application with VLISP projects. The features described in this section are the text editor search functions and the Make Application wizard.

Topics in this section

  • Opening a Project
  • Finding a String in Project Source Files
  • Including a Project in a Visual LISP Application


Opening a Project

Working with Existing Projects
Working with Existing Projects
Finding a String in Project Source Files
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Working with Existing Projects >
Opening a Project

To open an existing project, choose Project [image] Open Project from the VLISP menu:

If the project file you want to open is in the current directory, you can simply enter the project name here. If the project file is not in the current directory, or if you don't know what the current directory is, press the Browse button to obtain a standard Open dialog box.

Note that you can have more than one project open at a time. You can view a list of all open projects by choosing the Project menu and looking at the bottom of the menu displayed:

At any time, only one of the projects is active. The check mark in front of the project name indicates the active project. The commands in the Project menu, such as Load and Build, apply to the active project. These commands work the same when selected from a Project window.

If you attempt to open a project that has the same name as the active project (that is, the project file has the same name, but is in a different directory than the current active project), VLISP displays a message box asking you if you want to “relocate the project definition.” If you choose “Yes,” VLISP loads the new project file and replaces the active project. If you choose “No,” VLISP does not load the new project file, leaving the current active project in place.


Finding a String in Project Source Files

Opening a Project
Working with Existing Projects
Including a Project in a Visual LISP Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Working with Existing Projects >
Finding a String in Project Source Files

The VLISP text search function, described in Searching for Text, provides you with the ability to search all of a project's source files for a string of text.

For example, suppose in reviewing gpmain.lsp you see calls to a function called gp:getPointInput, and you cannot remember in which source file this function is defined. To search for it, choose Search [image] Find from the VLISP menu. In the Find dialog box, select Project in the list of Search options:

A Project selection field now appears at the bottom of the Find dialog box. If the name of the project you want to search is not already displayed in this field, choose it from the pull-down list. Choose the Find button to perform the search. VLISP displays the results in a Find Output window like the following:

The output shows that four files were searched (there are four source files in the project), and four occurrences of gp:getPointInput were found. The occurrences were found in two files; the defun for the function is in gp-io.lsp. You can open an editor window for the file by double-clicking anywhere within the highlighted text in the Find Output window. You can also press SHIFT + F11 to display the first source location at which the text string was found, and then repeatedly press F11 to view subsequent occurrences in the source files.


Including a Project in a Visual LISP Application

Finding a String in Project Source Files
Working with Existing Projects
Optimizing Application Code
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Working with Existing Projects >
Including a Project in a Visual LISP Application

After you've made changes to an application's source files, you'll want to incorporate those changes in the application's executable file. Making Application Modules showed you how to keep individual application files synchronized, so that the application executable contained the latest versions of all its source files. Defining the application files as members of a single project simplifies this process further. Instead of listing every source file in your application's Make file, you can point to the VLISP project file and use the project file to identify your source files.

To define an application that includes a Visual LISP project

  1. Choose File [image] Make Application [image] New Application Wizard from the VLISP menu to start the Make Application wizard.
  2. Select Expert mode, then press Next.
  3. Identify the directory path in which you want VLISP to save your application files, and enter a name for the application.

    Choose Next to continue.

  4. Choose Next to accept the default application options.
  5. In the LISP Files to Include dialog box, click the pull-down menu to the right of the Add button and choose Visual LISP project file as the type of file to include.

    Choose the Add button to display the Add Visual LISP Project Files dialog box.

  6. Specify the .prj file you created for the Lesson5 tutorial example, then press Open to add the file to your application. All the project's files will be included in the application.

    Choose Next to continue to the next step in the Make Application wizard.

  7. In the Resource Files to Include dialog box, click on the pull-down to the right of the Add button and choose DCL files, then press the Add button to display the dialog box for selecting the DCL files.

    Select the DCL file in the Tutorial\VisualLISP\Lesson5 directory, then press Open to add the file to your application.

    Choose Next to continue the Make Application wizard.

  8. Accept the default options in the remaining steps and complete the Make Application process.

    If you add files to the VLISP project you included in your application, the new files are automatically included the next time you build the application.


Optimizing Application Code

Including a Project in a Visual LISP Application
Maintaining Visual LISP Applications
Defining Build Options
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications >
Optimizing Application Code

The optimization features of VLISP can produce more efficient compiled files, and are useful as your programs grow in size and complexity. With the VLISP project management feature, you can tailor the optimization options to the specific needs of your application.

Topics in this section

  • Defining Build Options
  • Choosing a Compilation Mode
  • Choosing a Link Mode
  • Understanding Safe Optimization


Defining Build Options

Optimizing Application Code
Optimizing Application Code
Choosing a Compilation Mode
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code >
Defining Build Options

VLISP provides a number of options for compiling and linking a project's source code that affect the efficiency of the compiled code. For example, you can specify whether to create a separate FAS file for each source file or merge all compiled files into a single FAS file. You can choose to have the compiler remove the names of all local symbols from your compiled files. You specify these options in the Project Properties dialog box.

To specify project build options

  1. Open the project file (choose Project [image] Open Project from the VLISP menu).
  2. Choose the Project Properties button in the Project window toolbar.
  3. Select the Build Options tab in the Project Properties dialog box. VLISP displays the Build Options dialog box:

Some of the build options require extensive background information, which is provided in the following sections of this chapter. The build options are:

Compilation Mode

Choose between standard and optimized compilation. Optimized compilation creates smaller and faster programs but is not suited for every project. See Choosing a Compilation Mode for more information on this topic.

Merge Files Mode

Tell the compiler whether to create a separate FAS file for each source file, or to merge all compiled files into a single FAS file.

A single FAS file is faster to load and is required for certain types of optimization. Sometimes, however, you will prefer to load your code one file at a time. This is important if you have not completed the debugging or modification of the application's code. FAS files do not allow source code debugging, so it is recommended that you compile your code only after the initial debugging is done.

Edit Global Declarations

Create or edit a global declarations file for the project.

This feature is provided for compatibility with the Preview version of VLISP.

FAS Directory

Specify the directory for compiled files. If you indicate a relative path, VLISP applies it in relation to the project's home directory. If you leave the field blank, VLISP places compiled files in the same directory as the project definition (.prj) file.

Tmp Directory

Specify the directory for project-related temporary files. A relative path is applied in relation to the project's home directory.

Link Mode

Specify how function calls are to be optimized. This option is only available if optimized compilation is selected. Choose from the following:

  • Do not link: This results in indirect linking of functions. The compiler stores the address of the symbol naming the function.
  • Link: If selected, the compiler directly addresses function definitions and all calls where the functions are referenced.
  • Internal: This directly links function calls and removes (drops) the function names from the resulting FAS files.

See Choosing a Link Mode for further information on these options.

Localize Variables

If this option is selected, the compiler removes (drops) the names of all local symbols from compiled files and directly links their references, wherever possible. This means the program code points to the address where a variable is stored, not to a symbol used to find the address of the variable.

Safe Optimize

If this option is selected, this option directs the compiler to refuse some types of optimization, if there is a chance they will result in incorrect code. For more information on optimization, see Choosing a Compilation Mode below.

Message Mode

Select the level of detail you want VLISP to produce in its compilation reports. You can choose to receive a report showing only fatal errors (those causing compilation failure), a report showing errors and warning messages, or a full report showing errors, warnings, and compiler statistics.


Choosing a Compilation Mode

Defining Build Options
Optimizing Application Code
Analyzing for Optimization Correctness
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code >
Choosing a Compilation Mode

Combining compiled code from multiple files to a single binary file allows the compiler to add a high level of optimization. It also means that there are more choices to make.

When producing standard, non-optimized binary code, the VLISP compiler preserves the symbol names associated with functions and global variables, because these symbols may be referenced from other files. When the symbol is referenced, VLISP looks in a table to determine what area in memory is assigned to the symbol.

When optimizing code, the VLISP compiler assumes all files in a project work together to form a complete application. This allows the compiler to discard the symbol names and, when executing the code, jump directly to the memory location containing the value associated with the symbol.

Topics in this section

  • Analyzing for Optimization Correctness


Analyzing for Optimization Correctness

Choosing a Compilation Mode
Choosing a Compilation Mode
Choosing a Link Mode
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code > Choosing a Compilation Mode >
Analyzing for Optimization Correctness

Optimizing code may introduce bugs to software that runs perfectly when non-optimized. Also, the level of performance gain depends highly on the internal structure of the source code. LISP is a language in which you can easily write programs that create or modify functions at runtime. This use of the language by definition contradicts compile-time optimization.

The VLISP compiler analyzes the code it compiles and links, then it creates a report pointing you to all source code segments that may cause problems when optimized. If you do not receive any optimization warning messages, you can assume optimization did not introduce new problems to your code.

The compiler is able to detect most problematic situations in AutoLISP code. However, there are situations in which it is impossible to detect code that may become incorrect during the optimization. If your program uses one of the following constructs, the compiler will not be able to prove correctness of the optimized code definitively:

  • Interaction with external ObjectARX applications that set or retrieve AutoLISP variables
  • Dynamic calls to functions defined by other ObjectARX applications
  • Evaluation of dynamically built code using eval, apply, mapcar, or load
  • Use of set to set dynamically supplied variables
  • Dynamic (program evaluated) action strings in action_tile and new_dialog

Remember that any optimization will change program semantics. The compiler intends to preserve the behavior of project components relative to one another. The compiler cannot guarantee unchanged behavior between your project and external procedures. Typical effects of optimization include the following:

  • Outer applications and the VLISP Console window lose access to program functions and symbols.
  • Functions available from the Console window in interpreter mode are unknown in compiled mode.
  • Functions are available from the Console window, but redefining them does not change the program's behavior.


Choosing a Link Mode

Analyzing for Optimization Correctness
Optimizing Application Code
Understanding Safe Optimization
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code >
Choosing a Link Mode

If you instruct the VLISP compiler to link functions in your project directly, the compiler tries to resolve all explicit function calls by referencing the function's definition in memory. In contrast, when you indirectly link your functions, the compiler creates references to symbols that VLISP later uses to look up the actual memory location of the function. Direct linking improves the performance of the compiled code and protects the code against function redefinition. However, if your application needs to redefine a function, you cannot directly link that function.

Once function calls are directly linked, the compiler can optimize one level further by dropping the function name completely so that the function becomes invisible to users. To select this feature, choose the Internal Link mode option. Note that symbols exported to AutoCAD (for example, function names starting with C:) are never dropped.


Understanding Safe Optimization

Choosing a Link Mode
Optimizing Application Code
Optimization Conditions Bypassed by Safe Optimization
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code >
Understanding Safe Optimization

Choosing the Safe Optimize option reduces the amount of compiler optimization but protects your code against compiler-induced errors. Safe optimizing prevents runtime uncertainty that could cause an optimized program to fail, even though the source code seems to be correct. For example, imagine the following situation:

  • The function symbol fishlips is defined by defun and used somewhere in your code. This is a typical candidate for link optimization.
  • In another segment of your code, a variable named fishlips is assigned using (setq fishlips expression).

Now there are two possible conditions. If the value assigned through setq is intended to alter the definition of the function fishlips, direct linking will prevent this from happening. The first definition will be referenced directly and cannot be changed by the setq function. On the other hand, if the identical names are handled independently, fishlips can be linked without creating incorrect code.

If safe optimizing is on, the compiler will always stay on the safe side, even if you explicitly request that fishlips be directly linked. This may result in less efficient code, but it ensures code correctness. If safe optimizing is off, you can override the compiler's recommendation to link fishlips indirectly. You are responsible for the link option.

The Safe Optimize mode is on by default. Be sure you fully understand the consequences before you turn it off.

Topics in this section

  • Optimization Conditions Bypassed by Safe Optimization
  • Safe Optimization Warning Messages
  • Compiler Checking of Optimizing Conditions


Optimization Conditions Bypassed by Safe Optimization

Understanding Safe Optimization
Understanding Safe Optimization
Safe Optimization Warning Messages
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code > Understanding Safe Optimization >
Optimization Conditions Bypassed by Safe Optimization

When Safe Optimization is in effect, the VLISP compiler ignores an optimization option if it determines that adhering to the option may induce an error condition. The following list identifies the conditions under which an option is ignored:

Link

If the compiler encounters the following situations while Safe Optimize is on, it ignores any related Link directive:

  • A symbol is bound as a parameter anywhere in the project.
  • A symbol is bound as an auxiliary variable and referenced by value anywhere in the project.
  • A symbol is explicitly assigned somewhere (by setq).
Drop

If the compiler encounters a symbol referenced by value, it ignores any Drop directive for the symbol.

Localize

If the compiler encounters the following situations while safe optimize is on, it ignores the Localize directive or the corresponding variable:

  • A variable has a non-local reference or assignment to it within the project.
  • A variable is called by name.


Safe Optimization Warning Messages

Optimization Conditions Bypassed by Safe Optimization
Understanding Safe Optimization
Compiler Checking of Optimizing Conditions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code > Understanding Safe Optimization >
Safe Optimization Warning Messages

If optimized compilation is on and the compiler finds a condition that forbids a certain level of optimization, it issues a warning message. For example, if the function fishlips cannot be linked because the compiler found two definitions for the function, you'll see:

;*** WARNING: Cannot LINK fishlips;
 Two DEFUNs found.
See Another DEFUN

Right-click on a warning message to open a shortcut menu. In addition to displaying symbol commands, the menu allows you to view the source code associated with the message. Double-click on the highlighted message to show the source code. To browse all source files related to the compiler messages, press F11 repeatedly, or press SHIFT + F11 to return to the first message.

Each line of the previous warning message guides you to a different code segment. For example:

; *** WARNING: Cannot LINK fishlips

shows the function call that could not be linked.

; Two DEFUNs found

shows the first defun found for function fishlips.

; See Another DEFUN

shows the second defun found for function fishlips.

When the compiler works in Safe Optimization mode and finds a problem condition, the warning starts with:

; *** WARNING: Safe: Cannot …

If Safe Optimization is off, but message mode is set to Full report, the same warnings are prefixed by:

; *** WARNING: Dangerous …

If you disable Safe Optimize mode, these problematic conditions result in compiler warnings.


Compiler Checking of Optimizing Conditions

Safe Optimization Warning Messages
Understanding Safe Optimization
Working with ActiveX
AutoLISP Developer's Guide > Using the Visual LISP Environment > Maintaining Visual LISP Applications > Optimizing Application Code > Understanding Safe Optimization >
Compiler Checking of Optimizing Conditions

The compiler always checks for optimizing consistency. If you specify an optimization option that contradicts certain security rules, the compiler will issue warning messages. The security rules are:

Link

The compiler directly links AutoLISP function calls only if the following conditions are met:

  • The function is defined only once, or is predefined by AutoLISP and no user defun redefines it.
  • The function name does not appear in the parameter list of another function.
  • The function is not assigned anywhere in the project.
Drop

The compiler tries to drop a function symbol only if all corresponding function calls are directly linked to the function definition. The compiler does not drop the symbol for a function definition if the program calls the function by its symbol name. A function is called by symbol in the following cases:

  • The symbol appears in a vl-acad-defun declaration.
  • The function was called from an ACTION_TILE action string.
  • The function symbol is a quoted argument for apply, mapcar, or eval somewhere in the project.

Note that for functions called from top-level expressions, the Drop declaration will be ignored without warning messages.

Localize

The compiler does not localize a variable in bound lists of defun, lambda, and foreach expressions if any of the following conditions are true:

  • The variable has a non-local reference (or assignment) to it within the outer top-level expression.
  • The variable is called as a function by name.
  • The variable symbol appears as a function call somewhere in the top-level read-eval loop.

Other than these conditions, which always cancel the optimization and result in warning messages, there are other conditions that may or may not result in incorrect code. Choose the Safe Optimize option for the project to disallow these conditions as well. Disabling Safe Optimization results in compiler warnings if these conditions are met. See Understanding Safe Optimization for more information on this topic.


Working with ActiveX

Compiler Checking of Optimizing Conditions
Using the Visual LISP Environment
Using ActiveX Objects with AutoLISP
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Working with ActiveX

With Visual LISP, you can access the AutoCAD object model.

Visual LISP® not only makes program development easier and faster, it also provides new functionality to AutoLISP® applications. For example, you can use VLISP to access ActiveX® objects from AutoLISP code. You can also use ActiveX to interact with other Windows applications that support ActiveX methodology.

Topics in this section

  • Using ActiveX Objects with AutoLISP
  • Understanding the AutoCAD Object Model
  • Accessing AutoCAD Objects
  • Using Visual LISP Functions with ActiveX Methods
  • Using ActiveX to Interact with Other Applications


Using ActiveX Objects with AutoLISP

Working with ActiveX
Working with ActiveX
Understanding the AutoCAD Object Model
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX >
Using ActiveX Objects with AutoLISP

ActiveX Automation is a way to work programmatically with the contents of an AutoCAD® drawing. In many instances, ActiveX works faster than traditional AutoLISP functions in manipulating AutoCAD drawing objects.

The ActiveX programming interface is usable in a number of languages and environments. When you work with ActiveX objects in AutoLISP, you work with the same object model, properties, and methods that can be manipulated from other programming environments.

Objects are the main building blocks of an ActiveX application. In some ways, you are already familiar with this notion. For example, AutoCAD drawing items such as lines, arcs, polylines, and circles have long been referred to as objects. But in the ActiveX schema, the following AutoCAD components are also represented as objects:

  • Style settings, such as linetypes and dimension styles
  • Organizational structures, such as layers, groups, and blocks
  • The drawing display, such as the view and viewport
  • The drawing's model space and paper space

Even the drawing and the AutoCAD application itself are considered objects.

NoteTo access drawing properties such as Title, Subject, Author, and Keywords, the IAcadSummaryInfo interface, accessible as a property of the Document object in the AutoCAD object model, must be used. For more information, see Accessing Drawing Properties.

ActiveX includes much of the functionality provided by standard AutoLISP functions such as entget, entmod, and setvar. Compared to these functions, ActiveX runs faster and provides easier access to object properties. For example, to access the radius of a circle with standard AutoLISP functions, you must use entget to obtain a list of entities and assoc to find the property you want. You must also know the code number (DXF key value) associated with that property to obtain it with assoc, as shown in the following example:

(setq radius (cdr (assoc 40 (entget circle-entity))))

With an ActiveX function, you simply ask for the radius of a circle as follows:

(setq radius (vla-get-radius circle-object))


Understanding the AutoCAD Object Model

Using ActiveX Objects with AutoLISP
Working with ActiveX
Object Properties
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX >
Understanding the AutoCAD Object Model

AutoCAD objects are structured in a hierarchical fashion, with the Application object at the root. The view of this hierarchical structure is referred to as the object model. It shows you which object provides access to the next level of objects. The AutoCAD object model is described in the following figure:

Using ActiveX is not always a matter of choice. For example, you must use ActiveX to access drawing objects from reactor callback functions. You'll learn more about this in Attaching Reactors to AutoCAD Drawings.

Topics in this section

  • Object Properties
  • Object Methods
  • Collections of Objects


Object Properties

Understanding the AutoCAD Object Model
Understanding the AutoCAD Object Model
Object Methods
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Understanding the AutoCAD Object Model >
Object Properties

All objects in the AutoCAD object model have one or more properties. For example, a circle object can be described by properties such as radius, area, or linetype. An ellipse object also has area and linetype properties, but it cannot be described in terms of its radius. Rather, you describe it in terms of its major to minor axis ratio, a property named RadiusRatio. Property names are necessary when accessing AutoCAD data through ActiveX functions.


Object Methods

Object Properties
Understanding the AutoCAD Object Model
Collections of Objects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Understanding the AutoCAD Object Model >
Object Methods

ActiveX objects also contain methods, which are simply the actions available for a particular kind of object. Some methods can be applied to most AutoCAD drawing objects. For example, the Mirror method (creating a mirror image copy of an object around a mirror axis), and the Move method (moving a drawing object along a specified vector) can be applied to most drawing objects. By contrast, the Offset method, which creates a new object at a specified distance from an existing object, applies only to a few classes of AutoCAD objects such as Arc, Circle, Ellipse, and Line.

In VLISP, ActiveX methods are implemented as AutoLISP functions. You'll see many references to ActiveX functions in VLISP documentation, but keep in mind that in ActiveX terminology, they are always known as methods.

To determine which methods and properties apply to a specific type of AutoCAD object, refer to the ActiveX and VBA Reference. This reference is available from the VLISP and AutoCAD Help menus, or by opening the acadauto.chm file in the AutoCAD Help directory.

You will probably want to leave the ActiveX and VBA Reference open when you are developing VLISP programs that use ActiveX. If you open the acadauto.chm file from the AutoCAD Help directory, you can keep the reference open when you use VLISP online Help.

NoteYou can access the Help topic for a vlax- or vla- function by highlighting the text of the function in the VLISP editor and clicking the Help button on the Tools toolbar.


Collections of Objects

Object Methods
Understanding the AutoCAD Object Model
Accessing AutoCAD Objects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Understanding the AutoCAD Object Model >
Collections of Objects

All objects in the AutoCAD object model are grouped in collections. For example, the Blocks collection is made up of all blocks in an AutoCAD drawing, and the ModelSpace collection comprises all graphical objects (circles, lines, polylines, and so on) in the drawing's model space. Collections are labeled in the object model diagram.


Accessing AutoCAD Objects

Collections of Objects
Working with ActiveX
Using the Inspect Tool to View Object Properties
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX >
Accessing AutoCAD Objects

The Application object is the root object for the AutoCAD object model. From the Application object, you can access any of the other objects, or the properties or methods assigned to objects.

Before you can use ActiveX functions with AutoLISP, you need to load the supporting code that enables these functions. Issue the following function call to load ActiveX support:

(vl-load-com)

This function first checks if ActiveX support is already loaded; if so, the function does nothing. If ActiveX support is not already loaded, vl-load-com loads ActiveX and other Visual LISP extensions to the AutoLISP language.

NoteAll applications that use ActiveX should begin by calling vl-load-com. If your application does not call vl-load-com, the application will fail, unless the user has already loaded ActiveX support.

After loading the ActiveX support functions, the first step in accessing AutoCAD objects is to establish a connection to the AutoCAD Application object. Use the vlax-get-acad-object function to establish this connection, as in the following example:

(setq acadObject (vlax-get-acad-object))

The vlax-get-acad-object function returns a pointer to the AutoCAD Application object. In the example above, the pointer is stored in the acadObject variable. This return value exists as a unique VLISP data type called VLA-object (VLISP ActiveX object).

When you refer to AutoCAD objects with ActiveX functions, you must specify a VLA-object type. For this reason, you cannot use entget to access an object and then refer to that object with an ActiveX function. The entget function returns an object of data type ename. Although you cannot use this object directly with an ActiveX function, you can convert it to a VLA-object using the vlax-ename->vla-object function. (See Converting Object References.)

Topics in this section

  • Using the Inspect Tool to View Object Properties
  • Moving Forward from the Application Object
  • Summarizing the Process
  • Performance Considerations


Using the Inspect Tool to View Object Properties

Accessing AutoCAD Objects
Accessing AutoCAD Objects
Moving Forward from the Application Object
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Accessing AutoCAD Objects >
Using the Inspect Tool to View Object Properties

To view the properties associated with an Application object, you can select the variable that points to the object (acadobject, in the previous example), and choose the Inspect button on the VLISP View toolbar as follows:

You can readily identify many of the properties listed in the VLA-object Inspect window. For example, FullName is the file name of the AutoCAD executable file, Version is the current AutoCAD version, and Caption is the contents of the AutoCAD window title bar. An [RO] following a property name indicates the property is read-only; you cannot change it.

Any property identified as a #<VLA-OBJECT...> refers to another AutoCAD ActiveX object. Look at the Preferences property, for example. If you refer to the diagram of the AutoCAD object model, you'll see that the Preferences object is just below the Application object in the model hierarchy. To view the properties associated with an object, double-click the object line in the Inspect window (or right-click and choose Inspect). Here is the Inspect window for the Preferences object:

You may notice that the properties of the Preferences object correspond to the tabs on the AutoCAD Options dialog box. Double-click on the Files property to display the following Inspect window:

If you compare the properties shown in this window to the options available under the Files tab in the AutoCAD Options dialog box, you'll be able to see the connection between the two. The following figure shows the Files options:

For example, the AutoSavePath property corresponds to the Automatic Save File Location option, and the HelpFilePath property would be a sub-option under the Menu, Help, and Miscellaneous File Names option.

You'll learn how to use ActiveX functions to access objects and modify properties in Using Visual LISP Functions with ActiveX Methods.


Moving Forward from the Application Object

Using the Inspect Tool to View Object Properties
Accessing AutoCAD Objects
Summarizing the Process
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Accessing AutoCAD Objects >
Moving Forward from the Application Object

Following the AutoCAD object model hierarchy, the ActiveDocument property of the Application object leads you to a Document object. This Document object represents the current AutoCAD drawing. The following AutoLISP command returns the active document:

(setq acadDocument (vla-get-ActiveDocument acadObject))

The Document object has many properties. Access to non-graphical objects (layers, linetypes, and groups, for example) is provided through like-named properties such as Layers, Linetypes, and Groups. To get to the graphical objects in the AutoCAD drawing, you must access either the drawing's model space (through the ModelSpace property) or paper space (through the PaperSpace property). For example:

(setq mSpace (vla-get-ModelSpace acadDocument))

At this point, you have access to the AutoCAD drawing and can add objects to the drawing. For example, you can add a circle to the model space with the following command:

(setq mycircle (vla-addCircle mSpace
   (vlax-3d-point '(3.0 3.0 0.0)) 2.0))


Summarizing the Process

Moving Forward from the Application Object
Accessing AutoCAD Objects
Performance Considerations
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Accessing AutoCAD Objects >
Summarizing the Process

In this section, you saw code examples that led to the drawing of a circle object in an AutoCAD drawing using ActiveX Automation. The following sequence of function calls was used:

(vl-load-com)
(setq acadObject   (vlax-get-acad-object))
(setq acadDocument (vla-get-ActiveDocument acadObject))
(setq mSpace       (vla-get-ModelSpace acadDocument))
(setq mycircle    (vla-addCircle mSpace
     (vlax-3d-point '(3.0 3.0 0.0)) 2.0))

The statements in this example accomplished the following:

  • Loaded AutoLISP ActiveX support functions.
  • Returned a pointer to the Application object.
  • Obtained a pointer to the current active Document object, using the ActiveDocument property of the Application object. This provided access to the current AutoCAD drawing.
  • Obtained a pointer to the ModelSpace object, using the ModelSpace property of the Document object.
  • Drew a circle in the ModelSpace.

The hierarchical path traversed in the AutoCAD object model is pictured below:


Performance Considerations

Summarizing the Process
Accessing AutoCAD Objects
Using Visual LISP Functions with ActiveX Methods
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Accessing AutoCAD Objects >
Performance Considerations

Repeated calls to access the AutoCAD Application, active Document, and ModelSpace objects should be avoided, as they negatively impact performance. You should design your applications to obtain these objects one time, and refer to the obtained object pointers throughout the application.

The following code examples illustrate three functions you can define to return the Application, active Document, and ModelSpace objects, respectively:

(setq *acad-object* nil)      ; Initialize global variable
(defun acad-object ()
  (cond (*acad-object*)       ; Return the cached object
    (t
     (setq *acad-object* (vlax-get-acad-object))
    )
  )
)
(setq *active-document* nil)  ; Initialize global variable
(defun active-document ()
  (cond (*active-document*)   ; Return the cached object
    (t
     (setq *active-document* (vla-get-activedocument (acad-object)))
    )
  )
)
(setq *model-space* nil)      ; Initialize global variable
(defun model-space ()
  (cond (*model-space*)       ; Return the cached object
    (t
     (setq *model-space* (vla-get-modelspace (active-document)))
    )
  )
)

For example, you can draw a circle using the following function call:

(vla-addCircle (model-space) (vlax-3d-point '(3.0 3.0 0.0)) 2.0)

The model-space function returns the model space of the active document, using the active-document function to access the Document object, if necessary. The active-document function, in turn, calls acad-object to obtain the Application object, if necessary.


Using Visual LISP Functions with ActiveX Methods

Performance Considerations
Working with ActiveX
Determining the Visual LISP Function You Need
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX >
Using Visual LISP Functions with ActiveX Methods

VLISP adds a set of functions to the AutoLISP language that provides access to ActiveX objects. The function names are prefixed with vla-: for example, vla-addCircle, vla-get-ModelSpace, vla-getColor. These functions can be further categorized as follows:

  • vla- functions correspond to every ActiveX method. Use these functions to invoke the method (for example, vla-addCircle invokes the Addcircle method).
  • vla-get- functions correspond to every property, enabling you to retrieve the value of that property (for example, vla-get-Color obtains an object's color property).
  • vla-put- functions correspond to every property, enabling you to update the value of that property (for example, vla-put-Color updates an object's color property).

VLISP also adds a set of ActiveX-related functions whose names are prefixed with vlax-. These are more general ActiveX functions, each of which can be applied to numerous methods, objects, or properties. For example, with the vlax-get-property function, you can obtain any property of any ActiveX object. If your drawing contains custom ActiveX objects, or if you need to access objects from other applications, such as a Microsoft Excel spreadsheet, you can use the vlax-invoke-method, vlax-get-property, and vlax-put-property functions to access their methods and properties; you'll see examples using these functions in Using ActiveX without Importing a Type Library.

Topics in this section

  • Determining the Visual LISP Function You Need
  • Determining How to Call a Function
  • Converting AutoLISP Data Types to ActiveX Data Types
  • Viewing and Updating Object Properties
  • Using ActiveX Methods That Return Values in Arguments
  • Listing an Object's Properties and Methods
  • Working with Collection Objects
  • Releasing Objects and Freeing Memory
  • Converting Object References
  • Handling Errors Returned by ActiveX Methods


Determining the Visual LISP Function You Need

Using Visual LISP Functions with ActiveX Methods
Using Visual LISP Functions with ActiveX Methods
Determining How to Call a Function
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Determining the Visual LISP Function You Need

The VLISP ActiveX functions actually provide access to ActiveX methods. For example, look at the following AutoLISP statement, which was entered at the VLISP Console prompt:

_$ (setq mycircle (vla-addCircle
mSpace
      (vlax-3d-point
'(3.0 3.0 0.0)) 2.0))
#<VLA-OBJECT IAcadCircle 03ad067c>

This command adds a circle to a drawing, using the Addcircle method. The function called to draw the circle is vla-addCircle.

If you do not know what function adds a circle to an AutoCAD drawing, you can figure it out by looking in the ActiveX and VBA Reference. If you look up the definition for a Circle object, here's what the entry looks like:

Sometimes, as in this Circle entry, there is descriptive text that identifies the method you need. Often, though, you'll need to look through the list of methods to find the one that matches the action you want to take.

Once you find the name of the method, add a vla- prefix to the method name to get the name of the VLISP function that implements the method. In this example, it is vla-AddCircle. Note in VLISP the function name is not case-sensitive; vla-addcircle is the same as vla-AddCircle.


Determining How to Call a Function

Determining the Visual LISP Function You Need
Using Visual LISP Functions with ActiveX Methods
Converting AutoLISP Data Types to ActiveX Data Types
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Determining How to Call a Function

Once you identify the VLISP function you need, you still must determine how to call the function. You need to know the arguments to specify and the data type of those arguments. The ActiveX and VBA Reference contains the information required for coding calls to ActiveX functions.

For example, from the reference page for the Circle object, choose the AddCircle hyperlink to view the definition of this method:

Note that you can also get to this page by choosing the Methods button near the top of the Help window, then choosing AddCircle from a list of methods.

The syntax definitions in the reference were designed for Visual Basic 6 users, so they may take some getting used to. For AddCircle, the syntax is defined as follows:

RetVal = object.AddCircle(Center, Radius)

Substituting the variable names used in this chapter's examples, the syntax is:

mycircle = mspace.AddCircle(Center, Radius)

The AutoLISP syntax required for the same operation is:

(setq myCircle (vla-addCircle mSpace
   (vlax-3d-point '(3.0 3.0 0.0)) 2.0))

The return value (RetVal, in Visual Basic 6) is straightforward. The ActiveX and VBA Reference defines this as a Circle object. In VLISP, whenever an AutoCAD object is returned by an ActiveX function, it is stored as a VLA object data type.

The object referred to before the method name (object.AddCircle) is always the first argument in a vla function call. This is the AutoCAD object you are viewing or modifying. For example, add a circle to the drawing model space with the following:

(vla-addCircle  mSpace ...)

In this example, mspace refers to the ModelSpace object. Recall from the discussion on the AutoCAD object model (in Accessing AutoCAD Objects), that you use the properties of one AutoCAD object to access another object in a hierarchical manner. The ModelSpace object provides access to the model space of the current drawing.

The Center and Radius arguments refer to data types that may be unfamiliar to LISP users. The following section explains these data types.

Note that some ActiveX methods require arguments that are described as output only. See Using ActiveX Methods That Return Values in Arguments for information on how to code these arguments.


Converting AutoLISP Data Types to ActiveX Data Types

Determining How to Call a Function
Using Visual LISP Functions with ActiveX Methods
Working with Variants
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Converting AutoLISP Data Types to ActiveX Data Types

When adding a circle to a drawing, you must specify the center point of the circle and the radius of the circle. In the definition for the AddCircle method in the ActiveX and VBA Reference, these arguments are referred to as Center and Radius. Center is defined as a variant (three-element array of doubles), and Radius is listed as a double:

RetVal = object.AddCircle (Center, Radius)

Elements

Center

Variant (three-element array of doubles); input only. A 3D WCS coordinate specifying the circle's center.

Radius

Double; input only. The radius of the circle. Must be a positive number.

The reference explains what these parameters are used for, but the data types indicated for these parameters may be unfamiliar to LISP users. Variants are essentially self-defining structures that can contain different types of data. For example, strings, integers, and arrays can all be represented by variants. Stored along with the data is information identifying the type of data. This self-defining feature makes variants useful for passing parameters to ActiveX servers, because it enables servers based on any language to understand the data value.

Topics in this section

  • Working with Variants
  • Working with Safearrays
  • Using Safearrays with Variants
  • Converting Other AutoLISP Data Types for ActiveX Methods


Working with Variants

Converting AutoLISP Data Types to ActiveX Data Types
Converting AutoLISP Data Types to ActiveX Data Types
Working with Safearrays
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Converting AutoLISP Data Types to ActiveX Data Types >
Working with Variants

Several AutoLISP functions allow you to create and work with variants:

  • vlax-make-variant creates a variant.
  • vlax-variant-type returns the data type of a variant.
  • vlax-variant-value returns the value of a variant variable.
  • vlax-variant-change-type changes the data type of a variant variable.

The vlax-make-variant function accepts two arguments: value and type. The value argument is the value to be assigned to the variant. The type argument specifies the type of data to be stored in the variant. For type, specify one of the following constants:

vlax-vbEmpty

Uninitialized (default value)

vlax-vbNull

Contains no valid data

vlax-vbInteger

Integer

vlax-vbLong

Long integer

vlax-vbSingle

Single-precision floating-point number

vlax-vbDouble

Double-precision floating-point number

vlax-vbString

String

vlax-vbObject

Object

vlax-vbBoolean

Boolean

vlax-vbArray

Array

The constants evaluate to integer values. Because the integer values can change, you should always refer to the constant, not the integer value. See the entry for vlax-make-variant in the AutoLISP Reference for the current integer value assigned to each constant.

For example, the following function call creates an integer variant and sets its value to 5:

_$ (setq varint (vlax-make-variant
5 vlax-vbInteger))
#<variant 2 5>

The return value indicates the variant's data type (2, which is vbInteger) and the variant's value (5).

If you do not specify a data type to vlax-make-variant, the function assigns a default type. For example, the following function call creates a variant and assigns it a value of 5 but does not specify a data type:

_$ (setq varint (vlax-make-variant
5))
#<variant 3 5>

By default, vlax-make-variant assigned the specified integer value to a Long Integer data type, not Integer, as you might expect. When assigning a numeric value to a variant, you should explicitly state the data type you want. Refer to vlax-make-variant in the AutoLISP Reference for a complete list of default type assignments.

If you do not specify a value or data type, vlax-make-variant allocates an uninitialized (vlax-vbEmpty) variant.


Working with Safearrays

Working with Variants
Converting AutoLISP Data Types to ActiveX Data Types
Using Safearrays with Variants
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Converting AutoLISP Data Types to ActiveX Data Types >
Working with Safearrays

Arrays passed to ActiveX methods must be of the safearray type. These arrays are safe because you cannot accidentally assign values outside the array bounds and cause a data exception to occur. Use the vlax-make-safearray function to create a safearray and use vlax-safearray-put-element or vlax-safearray-fill to populate a safearray with data.

The vlax-make-safearray function requires a minimum of two arguments. The first argument identifies the type of data that will be stored in the array. Specify one of the following constants for the data type:

vlax-vbInteger

Integer

vlax-vbLong

Long integer

vlax-vbSingle

Single-precision floating-point number

vlax-vbDouble

Double-precision floating-point number

vlax-vbString

String

vlax-vbObject

Object

vlax-vbBoolean

Boolean

vlax-vbVariant

Variant

The constants evaluate to integer values. Because the integer values can change, you should always refer to the constant, not the integer value. See the entry for vlax-make-safearray in the AutoLISP Reference for the current integer value assigned to each constant.

The remaining arguments to vlax-make-safearray specify the upper and lower bounds of each dimension of the array. You can create single or multidimensional arrays with vlax-make-safearray. The lower bound for an index can be zero or any positive or negative integer.

For example, the following function call creates a single-dimension array consisting of doubles, with a starting index of 0:

_$ (setq point (vlax-make-safearray
vlax-vbDouble '(0 . 2)))
#<safearray...>

The upper bound specified in this example is 2, so the array will hold three elements (element 0, element 1, and element 2).

Different dimensions can have different bounds. For example, the following function call creates a two-dimension array of strings. The first dimension starts at index 0 and contains two elements, while the second dimension starts at index 1 and contains three elements:

_$ (setq mat2 (vlax-make-safearray
vlax-vbString '(0 . 1) '(1 . 3)))
#<safearray...>

You can use either vlax-safearray-fill or vlax-safearray-put-element to populate arrays with data.

Using vlax-safearray-fill

The vlax-safearray-fill function requires two arguments: the variable containing the array you are populating and a list of the values to be assigned to the array elements. You must specify as many values as there are elements in the array. For example, the following code populates a single-dimension array of three doubles:

(vlax-safearray-fill point '(100 100 0))

You can display the contents of this array in list form with the vlax-safear-ray->list function:

_$ (vlax-safearray->list
point)
(100.0 100.0 0.0)

If you do not specify a value for every element in the array, vlax-safear-ray-fill results in an error.

To assign values to a multi-dimensional array, specify a list of lists to vlax-safearray-fill, with each list corresponding to a dimension. For example, the following command assigns values to a two-dimension array of strings that contains three elements in each dimension:

_$ (vlax-safearray-fill
mat2 '(("a" "b" "c") ("d" "e" "f")))
#<safearray...>

Use the vlax-safearray->list function to confirm the contents of mat2:

_$ (vlax-safearray->list
mat2)
(("a" "b" "c") ("d" "e" "f"))

Using vlax-safearray-put-element

The vlax-safearray-put-element function can be used to assign values to one or more elements of a safearray. The number of arguments required by this function depends on the number of dimensions in the array. The following rules apply to specifying arguments to vlax-safearray-put-element:

  • The first argument always names the safearray to which you are assigning a value.
  • The next set of arguments identifies index values pointing to the element to which you are assigning a value. For a single-dimension array, specify one index value; for a two-dimension array, specify two index values, and so on.
  • The final argument is always the value to be assigned to the safearray element.

For example, the following code populates a single-dimension array of three doubles:

(vlax-safearray-put-element point 0 100)
(vlax-safearray-put-element point 1 100)
(vlax-safearray-put-element point 2 0)

To change the second element of the array to a value of 50, issue the following command:

(vlax-safearray-put-element point 1 50)

The following example populates a two-dimension array of strings. The first dimension of the array starts at index 0, while the second dimension starts at index 1:

(vlax-safearray-put-element mat2 0 1 "a")
(vlax-safearray-put-element mat2 0 2 "b")
(vlax-safearray-put-element mat2 0 3 "c")
(vlax-safearray-put-element mat2 1 1 "d")
(vlax-safearray-put-element mat2 1 2 "e")
(vlax-safearray-put-element mat2 1 3 "f")

You can use vlax-safearray->list to confirm the contents of the array:

_$ (vlax-safearray->list
mat2)
(("a" "b" "c") ("d" "e" "f"))


Using Safearrays with Variants

Working with Safearrays
Converting AutoLISP Data Types to ActiveX Data Types
Converting Other AutoLISP Data Types for ActiveX Methods
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Converting AutoLISP Data Types to ActiveX Data Types >
Using Safearrays with Variants

Safearray data must be passed to ActiveX methods through variants. That is, you create a safearray, then you assign the safearray to a variant before passing it to a method. For methods that require you to pass a three-element array of doubles (typically to specify a point), you can use the vlax-3d-point function to build the required data structure. For example, the following call takes a list of points and converts the list into an array of three doubles:

_$ (setq circCenter
(vlax-3d-point '(3.0 3.0 0.0)))
#<variant 8197 ...>

You can also pass vlax-3d-point two or three numbers, instead of a list. For example:

$ (setq circCenter
(vlax-3d-point 3.0 3.0))
#<variant 8197 ...>

When you omit the third point from your argument, vlax-3d-point sets it to zero. You can use vlax-safearray->list to verify the contents of the variable set by vlax-3d-point:

$ (vlax-safearray->list
(vlax-variant-value circcenter))
(3.0 3.0 0.0)

The vlax-TMatrix function performs a similar task for transformation matrices, which are required by the vla-TransformBy function. It builds the transformation matrix from four lists of four numbers each, converting all numbers to reals, if necessary. For example:

_$ (vlax-tmatrix '((1
1 1 0) (1 2 3 0) (2 3 4 5) (2 9 8 3)))
#<variant 8197 ...>

If you need to create a variant for an array containing anything other than three doubles or a transformation matrix, you must build it yourself.

To create a variant containing an array of four doubles

  1. Allocate space for the array:
    (setq 4dubs (vlax-make-safearray
vlax-vbDouble '(0 . 3)))
  2. Populate the array:
    (vlax-safearray-fill
4dubs '(3.0 6.0 7.2 1.0))
  3. Store the safearray in a variant:
    (setq var4dubs (vlax-make-variant
4dubs))

    The var4dubs variable now contains a variant containing an array of doubles.


Converting Other AutoLISP Data Types for ActiveX Methods

Using Safearrays with Variants
Converting AutoLISP Data Types to ActiveX Data Types
Viewing and Updating Object Properties
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Converting AutoLISP Data Types to ActiveX Data Types >
Converting Other AutoLISP Data Types for ActiveX Methods

The Radius argument to the AddCircle method requires a Double, but the ActiveX functions make the necessary conversion if you specify a real in AutoLISP. The following table identifies the AutoLISP data type that ActiveX functions will accept in place of the required ActiveX data type. Each row in the table represents a data type used by ActiveX functions. Each column in the table represents an AutoLISP data type. Wherever the intersecting cells contain a plus (+) symbol, you can specify the corresponding AutoLISP data type for the required ActiveX data type.

AutoLISP data types accepted in place of an ActiveX data type
 | Integer | Real | String | VLA-object | Variant | Safe-array | :vlax-true :vlax-false
Byte | + |  |  |  |  |  |
Boolean |  |  |  |  |  |  | +
Integer | + |  |  |  |  |  |
Long | + |  |  |  |  |  |
Single | + | + |  |  |  |  |
Double | + | + |  |  |  |  |
Object |  |  |  | + |  |  |
String |  |  | + |  |  |  |
Variant |  |  |  |  | + |  |
Array |  |  |  |  |  | + |

In some instances an AutoLISP ActiveX function will accept and convert a data type that is not indicated as acceptable by the preceding table, but you should never count on this.


Viewing and Updating Object Properties

Converting Other AutoLISP Data Types for ActiveX Methods
Using Visual LISP Functions with ActiveX Methods
Reading Object Properties
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Viewing and Updating Object Properties

VLISP provides AutoLISP functions for reading and updating object properties. You can use these functions to obtain the properties of existing drawing objects (for example, the center point of a circle), and to modify drawing objects (for example, moving the center point of the circle).

Topics in this section

  • Reading Object Properties
  • Updating Object Properties
  • Determining Whether an Object Is Available for Updating


Reading Object Properties

Viewing and Updating Object Properties
Viewing and Updating Object Properties
Updating Object Properties
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Viewing and Updating Object Properties >
Reading Object Properties

Functions that read object properties are named with a vla-get prefix and require the following syntax:

(vla-get-propertyobject)

For example, vla-get-center returns the center point of a circle.

To obtain an object's property and apply the property to a new object

  1. Enter the following at the VLISP Console prompt:
    (setq myCircle (vla-addcircle
mspace (vlax-3d-point
      (getpoint "\nPick
the center point for a circle: ")) 2.0))

    This function call prompts you to pick a center point for a circle, then invokes the Addcircle method to draw the circle. The vlax-3d-point function converts the point you pick into the data type required by vla-addcir-cle.

  2. Use vla-get-center to draw a second circle concentric to the first:
    (vla-addCircle mSpace
(vla-get-center myCircle) 1.0)

    The AutoCAD drawing window now contains the following objects:


Updating Object Properties

Reading Object Properties
Viewing and Updating Object Properties
Determining Whether an Object Is Available for Updating
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Viewing and Updating Object Properties >
Updating Object Properties

Functions that update properties are prefixed with vla-put and use the following syntax:

(vla-put-propertyobjectnew-value)

For example, vla-put-center changes the center point of a circle.

To change the X axis of a circle

  1. Obtain the current center point of the circle:
    _$ (setq myCenter (vla-get-center
myCircle))
    #<variant 8197

    The center point is returned in a variant of type safearray. The safearray contains three doubles (X, Y, and Z coordinates).

  2. Save the center point in list form:
    $ (setq centerpt (vlax-safearray->list
      (vlax-variant-value
myCenter)))
    (17.8685 5.02781 0.0)

    Converting the center point from a variant safearray to a list makes it easier to modify the coordinates.

  3. Subtract 1 from the X axis of the center point:
    _$ (setq newXaxis (-
(car centerpt) 1))
    16.8685

    The result is saved in variable newXaxis.

  4. Construct a new point list for the center point, using the new X axis and the original Y and Z values:
    _$ (setq newcenter (list
newXaxis  (cadr centerpt)
       (caddr centerpt)))
    (16.8685 4.52594 0.0)

    The constructed list is saved in variable newcenter.

  5. Use vla-put-center to update the circle with the new X axis:
    _$ (vla-put-center myCircle
(vlax-3d-point newcenter))
    nil

    Note that this command uses vlax-3d-point to convert the new center point list into the data type required by vla-put-center.

    The AutoCAD drawing window shows the result:

Note that changing an object's property may not immediately affect the display of the object in the AutoCAD drawing. AutoCAD delays property changes to allow you to change more than one property at a time. If you need to update the drawing window explicitly, issue the vla-update function:

(vla-update object)

Sometimes you can use pre-defined constants to update an object's property. For example, to set the fill color of a circle to red, you can use the constant acRed instead of specifying a numeric index value:

(vla-put-color myCircle acRed)

The ActiveX and VBA Reference lists any predefined constants under the entry describing the property. You can use these constants in VLISP ActiveX function calls.


Determining Whether an Object Is Available for Updating

Updating Object Properties
Viewing and Updating Object Properties
Using ActiveX Methods That Return Values in Arguments
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Viewing and Updating Object Properties >
Determining Whether an Object Is Available for Updating

If other applications are working with any AutoCAD objects at the same time as your program, those objects may not be accessible. This is especially important to look out for if your application includes reactors, because reactors execute code segments in response to external events that cannot be predicted in advance (see Attaching Reactors to AutoCAD Drawings). Even a simple thing such as a locked layer can prevent you from changing an object's properties.

VLISP provides the following functions to test the accessibility of an object before trying to use the object:

  • vlax-read-enabled-p tests whether you can read an object.
  • vlax-write-enabled-p determines whether you can modify an object's properties.
  • vlax-erased-p checks to see if an object has been erased. Erased objects may still exist in the drawing database.

These test functions return T if true, nil if false. The following examples test a line object:

Determine whether the line is readable:

$ (vlax-read-enabled-p
WhatsMyLine)
T

Determine whether the line is modifiable:

$ (vlax-write-enabled-p
WhatsMyLine)
T

See if the line has been erased:

$ (vlax-erased-p WhatsMyLine)
nil

Erase WhatsMyLine:

_$ (vla-delete WhatsMyLine)
nil

Issue vlax-read-enabled-p to see if WhatsMyLine is still readable:

$ (vlax-read-enabled-p
WhatsMyLine)
nil

Issue vlax-erased-p again to confirm the object was deleted:

$ (vlax-erased-p WhatsMyLine)
T


Using ActiveX Methods That Return Values in Arguments

Determining Whether an Object Is Available for Updating
Using Visual LISP Functions with ActiveX Methods
Listing an Object's Properties and Methods
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Using ActiveX Methods That Return Values in Arguments

Some ActiveX methods require that you supply them with variables into which the methods can place values. The GetBoundingBox method is an example of this type of method. Here is how it is defined in the ActiveX and VBA Reference:

Note that the MinPoint and MaxPoint parameters are described as output only. You must provide output arguments as quoted variable names. The following example shows a VLISP function call to return the minimum and maximum bounding points of a circle:

_$ (vla-getboundingbox
myCircle 'minpoint 'maxpoint)
nil

The values output by vla-getboundingbox are stored in the minpoint and maxpoint variables as safearrays of three doubles. You can view the values using vlax-safearray->list:

_$ (vlax-safearray->list
minpoint)
(1.0 1.0 -1.0e-008)
_$ (vlax-safearray->list
maxpoint)
(5.0 5.0 1.0e-008)

Note that the quoted symbol parameters you pass to the function become AutoLISP variables just like the ones created through setq. Because of this, you should include them as local variables in your function definition so they do not become global variables by default.


Listing an Object's Properties and Methods

Using ActiveX Methods That Return Values in Arguments
Using Visual LISP Functions with ActiveX Methods
Determining If a Method or Property Applies to an Object
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Listing an Object's Properties and Methods

Earlier in this chapter, you learned how to use the VLISP Inspect tool to display an object's properties. Another way to view an object's properties is to call the vlax-dump-object function. You can invoke this function from the VLISP Console window or from an application program. The vlax-dump-object function prints a list of the properties of the specified object and returns T. For example, the following code obtains the last object added to the model space, then issues vlax-dumpObject to print the object's properties:

_$ (setq WhatsMyLine
(vla-item mSpace (- (vla-get-count mspace) 1)))
#<VLA-OBJECT IAcadLWPolyline 036f1d0c>
_$ (vlax-dump-object
WhatsMyLine)
; IAcadLWPolyline: AutoCAD Lightweight Polyline Interface
; Property values:
;   Application (RO) = #<VLA-OBJECT IAcadApplication 00a4ae24>
;   Area (RO) = 2.46556
;   Closed = 0
;   Color = 256
;   ConstantWidth = 0.0
;   Coordinate = ...Indexed contents not shown...
;   Coordinates = (8.49917 7.00155 11.2996 3.73137 14.8 5.74379 ... )
;   Database (RO) = #<VLA-OBJECT IAcadDatabase 01e3da44>
;   Elevation = 0.0
;   Handle (RO) = "53"
;   HasExtensionDictionary (RO) = 0
;   Hyperlinks (RO) = #<VLA-OBJECT IAcadHyperlinks 01e3d7d4>
;   Layer = "0"
;   Linetype = "BYLAYER"
;   LinetypeGeneration = 0
;   LinetypeScale = 1.0
;   Lineweight = -1
;   Normal = (0.0 0.0 1.0)
;   ObjectID (RO) = 28895576
;   ObjectName (RO) = "AcDbPolyline"
;   PlotStyleName = "ByLayer"
;   Thickness = 0.0
;   Visible = -1
T

There is an optional second argument you can supply to vlax-dump-object that causes it to also list all the methods that apply to the object. Simply specify “T” following the object name:

(vlax-dump-object WhatsMyLine T)

Note that vlax-dump-object displays the information in the window from which you issued the command. However, the function returns T to the calling program, not the information displayed in the Command window.

Topics in this section

  • Determining If a Method or Property Applies to an Object


Determining If a Method or Property Applies to an Object

Listing an Object's Properties and Methods
Listing an Object's Properties and Methods
Working with Collection Objects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Listing an Object's Properties and Methods >
Determining If a Method or Property Applies to an Object

Trying to use a method that does not apply to the specified object will result in an error. Trying to reference a property that does not apply to an object also results in an error. In instances where you are not sure what applies, use the vlax-method-applicable-p and vlax-property-available-p functions to test the objects. These functions return T if the method or property is available for the object, and nil if it is not.

The syntax for vlax-method-applicable-p is:

(vlax-method-applicable-p objectmethod)

The following command checks to see if the Copy method can be applied to the object referenced by WhatsMyLine:

_$ (vlax-method-applicable-p
WhatsMyLine "Copy")
T

The following command determines whether or not the AddBox method can be applied to the object:

_$ (vlax-method-applicable-p
WhatsMyLine "AddBox")
nil

For vlax-property-available-p, the syntax is:

(vlax-property-available-p objectproperty [T])

For example, the following commands determine if Color and Center are properties of WhatsMyLine:

_$ (vlax-property-available-p
WhatsMyLine "Color")
T
_$ (vlax-property-available-p
WhatsMyLine "Center")
nil

Supplying the optional “T” argument to vlax-property-available-p changes the meaning of the test. If you supply this argument, the function returns T only if the object has the property and the property can be modified. If the object has no such property or the property is read-only, vlax-property-available-p returns nil. For example, an ellipse contains an Area property, but you cannot update it. If you check the property without specifying the optional argument, the result is T:

_$ (vlax-property-available-p
myEllipse "area")
T

If you supply the optional argument, the result is nil:

_$ (vlax-property-available-p
myEllipse "area" T)
nil


Working with Collection Objects

Determining If a Method or Property Applies to an Object
Using Visual LISP Functions with ActiveX Methods
Retrieving Member Objects in a Collection
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Working with Collection Objects

The concept of collections was introduced in Understanding the AutoCAD Object Model Recall that all ActiveX objects in the AutoCAD object model are grouped in collections. For example, the Blocks collection is made up of all blocks in an AutoCAD document. VLISP provides functions to help you work with collections of AutoCAD objects. These functions are vlax-map-collection and vlax-for.

The vlax-map-collection function applies a function to every object in a collection. The syntax is:

(vlax-map-collection collection-objectfunction)

For example, the following command displays all properties of every object in a drawing's model space:

$ (vlax-map-collection
(vla-get-ModelSpace acadDocument) 'vlax-dump-Object)
; IAcadLWPolyline: AutoCAD Lightweight Polyline Interface
; Property values:
;   Application (RO) = #<VLA-OBJECT IAcadApplication 00b3b91c>
;   Area (RO) = 3.67152
;   Closed = -1
;   Color = 256
;   Coordinates = (9.59247 4.44872 9.25814 5.34715 4.1991 5.679 ...)
;   EntityName (RO) = "AcDbPolyline"
;   EntityType (RO) = 24
;   Handle (RO) = "4C"
;   Layer = "0"
;  .
;  .
;  .
;   Thickness = 0.0
;   Visible = -1

(Note that the preceding example does not show every property returned by vlax-dump-Object.)

To evaluate a series of functions with each object in a collection, use vlax-for:

(vlax-for symbolcollection [expressions] ...)

Like the foreach function, vlax-for returns the result of the last expression evaluated inside the for loop. Note that modifying the collection (that is, adding or removing members) while iterating through it may cause an error.

The following example defines a function that uses vlax-for to show color statistics for each object in the active drawing:

(defun show-Color-Statistics (/ objectColor colorSublist colorList)
   (setq modelSpace (vla-get-ModelSpace
       (vla-get-ActiveDocument (vlax-get-Acad-Object))
    )
   )
   (vlax-for obj modelSpace
      (setq objectColor (vla-get-Color obj))
      (if (setq colorSublist (assoc objectColor colorList))
        (setq colorList
           (subst (cons objectColor (1+(cdr colorSublist)))
                          colorSublist
                          colorList
           )
        )
        (setq colorList (cons (cons objectColor 1) colorList))
     )
  )
  (if colorList
     (progn (setq
        colorList (vl-sort colorList
                    '(lambda (lst1 lst2) (< (car lst1) (car lst2)))
                  )
            )
            (princ "\nColorList = ")
            (princ colorList)
            (foreach subList colorList
               (princ "\nColor ")
               (princ (car subList))
               (princ " is found in ")
               (princ (setq count (cdr subList)))
               (princ " object")
               (princ (if (= count 1)
                         "."
                         "s."
                       )
 )    )    )   )
 (princ)
)

This function lists each color in the drawing and the number of objects where the color is found.

Topics in this section

  • Retrieving Member Objects in a Collection


Retrieving Member Objects in a Collection

Working with Collection Objects
Working with Collection Objects
Releasing Objects and Freeing Memory
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Working with Collection Objects >
Retrieving Member Objects in a Collection

The Item method retrieves a member object from a collection. The Count property shows the number of items in a collection. Using the Item method and Count property, you can individually process each object in a collection. For example, you can look at each object in a model space, determine the type of object, and process only the types of objects you are interested in. The following code prints the start angle for each arc object in a model space:

(setq index 0)
(repeat   (vla-get-count mspace)
  (if (= "AcDbArc" (vla-get-objectname (vla-item mspace index)))
    (progn
      (princ "\nThe start angle of the arc is ")
      (princ (vla-get-startangle (vla-item mspace index)))
    )
  )
  (setq index (+ index 1))
)

Note that Item and Count also apply to groups and selection sets.


Releasing Objects and Freeing Memory

Retrieving Member Objects in a Collection
Using Visual LISP Functions with ActiveX Methods
Converting Object References
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Releasing Objects and Freeing Memory

Just as you can have different variables pointing to the same AutoCAD entity, you can have multiple VLA-objects pointing to the same drawing object. You can compare two VLA-objects with the equal function, which returns T if both objects point to the same drawing object.

As long as a VLA-object points to a drawing object, AutoCAD will keep all the memory needed for the object. When you no longer need to reference an object, use the vlax-release-object function to indicate this to AutoCAD:

(vlax-release-object object)

After releasing an object, it is no longer accessible through the VLA-object pointer. This is similar to closing a file. No memory is necessarily freed when you issue vlax-release-object, but AutoCAD can reclaim the memory if needed, once all references to the object have been released.

To test whether or not an object has been released, use the vlax-object-released-p function:

(vlax-object-released-p object)

This function returns T if the object has been released, nil if it has not.


Converting Object References

Releasing Objects and Freeing Memory
Using Visual LISP Functions with ActiveX Methods
Converting between Enames and VLA-objects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Converting Object References

There are a number of ways to refer to AutoCAD drawing objects with AutoLISP. These include the following:

  • VLA-objects, returned by ActiveX functions
  • Entity names (enames), returned by entget and entsel, identifying objects in an open drawing
  • Handles, returned by handent, which entities retain across AutoCAD sessions
  • Object IDs, used by ARX to identify objects

AutoLISP provides functions to convert from one type of object identifier to another.

Topics in this section

  • Converting between Enames and VLA-objects
  • Obtaining One Object Identifier from Another


Converting between Enames and VLA-objects

Converting Object References
Converting Object References
Obtaining One Object Identifier from Another
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Converting Object References >
Converting between Enames and VLA-objects

The vlax-ename->vla-object function allows you to convert entity names (enames) obtained through functions, such as entget, to VLA-objects you can use with ActiveX functions. For example, the following code sets a variable to an ename, then uses vlax-ename->vla-object to convert the ename to a VLA-object:

_$ (setq ename-circle
(car (entsel "\nPick a Circle:")))
<Entity name: 27f0538>
_$ (setq vlaobject-circle
(vlax-ename->vla-object ename-circle))
#<VLA-OBJECT IAcadCircle 03642c24>

To convert VLA-objects to enames, use vlax-vla-object->ename. For example:

$ (setq new-ename-circle
(vlax-vla-object->ename vlaobject-circle))
<Entity name: 27f0538>


Obtaining One Object Identifier from Another

Converting between Enames and VLA-objects
Converting Object References
Handling Errors Returned by ActiveX Methods
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods > Converting Object References >
Obtaining One Object Identifier from Another

You may find the same drawing object represented by different identifiers and data types such as a handle string, an ename, a VLA-object, or an ObjectARX object ID integer. To obtain the identifier with the data type your program requires, use the following strategies:

  • To find the handle associated with an ename, use the DXF 5 group of the ename's association list:

    _$ (setq handle-circle (cdr (assoc 5 (entget ename-circle))))

    "4F"

  • To find the ename associated with a handle, use the handent function:

    _$ (handent handle-circle)

    <Entity name: 27f0538>

  • To find the VLA-object associated with a handle, use the vla-handleToObject function:

    _$ (setq vla-circle (vla-handleToObject acadDocument

    handle-circle))

    #<VLA-OBJECT IAcadCircle 03642c24>

  • To find the handle associated with a VLA-object, use vla-get-handle to obtain the handle property:

    _$ (vla-get-handle vla-circle)

    "4F"

  • To find the ObjectARX object ID of a VLA-object, use vla-get-objectid to get the objectID property:

    _$ (setq objid-Circle (vla-get-objectid vla-circle))

    41878840

  • To find the VLA-object identified by an ObjectARX object ID, use the ObjectID-toObject method on the AutoCAD Document object:

    _$ (vla-ObjectIDtoObject acadDocument objid-circle)

    #<VLA-OBJECT IAcadCircle 03642c24>


Handling Errors Returned by ActiveX Methods

Obtaining One Object Identifier from Another
Using Visual LISP Functions with ActiveX Methods
Using ActiveX to Interact with Other Applications
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using Visual LISP Functions with ActiveX Methods >
Handling Errors Returned by ActiveX Methods

When ActiveX methods fail, they raise exceptions rather than returning error values that your program can interpret. If your program uses ActiveX methods, you must prepare it to catch exceptions, otherwise the program halts, leaving the user at a Command prompt. You can use vl-catch-all-apply to intercept errors returned by ActiveX methods.

To intercept errors returned by ActiveX methods

  1. Load the following function and invoke it by issuing (init-motivate) at the VLISP Console prompt:
    (defun init-motivate ()
      (vl-load-com)
      (setq mspace
         (vla-get-modelspace
           (vla-get-activedocument (vlax-get-acad-object))
         )
      )
      (vla-addray mspace (vlax-3d-point 0 0 0) (vlax-3d-point 1 1 0))
    )

    This function adds a ray object to the current model space. A ray has a finite starting point and extends to infinity.

  2. The GetBoundingBox method obtains two points of a box enclosing a specified object, returning those points in variables you supply to the method. (See Using ActiveX Methods That Return Values in Arguments for an example using this.) The following code obtains a pointer to the last object added to a drawing's model space and uses vla-getboundingbox to obtain the points enclosing the object:
    (defun bnddrop (/ bbox)
      (setq bbox (vla-getboundingbox
               (vla-item mspace (- 1 (vla-get-count mspace)))
               'll
               'ur
             )
      )
      (list "Do something with bounding box." bbox)
    )

    Load this code and run it by issuing (bnddrop) at the Console prompt. Because a ray extends to infinity, it is not possible to enclose it with a box, and GetBoundingBox results in the following error:

    ; error: Automation Error. Invalid extents

    If this code were part of your application program, execution would halt at this point.

  3. By invoking vla-getboundingbox through the vl-catch-all-apply function, you can intercept errors returned by ActiveX. Load the following code and run it by issuing (bndcatch) at the Console prompt:
    (defun bndcatch (/ bbox)
      (setq bbox (vl-catch-all-apply
               'vla-getboundingbox
               (list (vla-item mspace (- 1 (vla-get-count mspace)))
                     'll
                     'ur
               )
             )
      )
      (if (vl-catch-all-error-p bbox)
        (list "Exception: " (vl-catch-all-error-message bbox))
        (list "Do something with bounding box." bbox)
      )
    )

    This function uses vl-catch-all-apply to call vla-getboundingbox. It passes vl-catch-all-apply two arguments: the symbol naming the function being called ('vla-getboundingbox) and a list of arguments to be passed to vla-getboundingbox. If the GetBoundingBox method completes successfully, vl-catch-all-apply stores the return value in variable bbox. If the call is unsuccessful, vl-catch-all-apply stores an error object in bbox.

    At this point in the bnddrop function, vla-getboundingbox was issued directly, an error resulted, and execution halted. But in bndcatch, vl-catch-all-apply intercepts the error and program execution continues.

    A call to vl-catch-all-error-p checks the return value from vl-catch-all-apply and returns T if it is an error object, nil otherwise. If the return value is an error object, as it would be in this example, the function issues vl-catch-all-error-message to obtain the message from the error object. Program execution continues from this point.

    Catching Errors and Continuing Program Execution includes a non-ActiveX example that uses the vl-catch-* functions to intercept errors. For additional information on these functions, see the AutoLISP Reference.


Using ActiveX to Interact with Other Applications

Handling Errors Returned by ActiveX Methods
Working with ActiveX
Importing a Type Library
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX >
Using ActiveX to Interact with Other Applications

The power of ActiveX extends beyond the ability to interact with standard AutoCAD objects. Visual LISP provides AutoLISP functions that allow you to access objects from other applications that support ActiveX. For example, you can open a Microsoft® Word document, retrieve text data from an AutoCAD drawing, and copy the text into the Word document. Or you might access cells in a Microsoft Excel spreadsheet and use the data with your AutoCAD drawing.

To write AutoLISP code that interacts with other ActiveX applications, you'll need to refer to the documentation for those applications to learn the application's object names and how to work with its methods and properties. Typically, the online Help for an ActiveX-enabled Windows application contains information on its ActiveX interface. For example, AutoCAD provides the ActiveX and VBA Reference, as well as the ActiveX and VBA Developer's Guide for working with ActiveX using Visual Basic for Applications (VBA).

The following topics in this section apply when you work with any ActiveX application from AutoLISP. The code examples illustrate the process of obtaining text from an AutoCAD drawing and then inserting the text into a Microsoft Word document.

Topics in this section

  • Importing a Type Library
  • Establishing a Connection to an Application
  • Coding a Sample Application
  • Using ActiveX without Importing a Type Library


Importing a Type Library

Using ActiveX to Interact with Other Applications
Using ActiveX to Interact with Other Applications
Coding Hints for Using vlax-import-type-library
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications >
Importing a Type Library

VLISP provides an AutoLISP function that allows you to import the type library of the ActiveX application you want to access. When you import a type library, AutoCAD creates a set of wrapper functions that provide access to the application's methods and properties. In fact, the vla- functions you have seen so far are wrapper functions created for the AutoCAD type library.

Use the vlax-import-type-library function to import a type library. When calling this function, identify the type library and tell AutoCAD what prefixes to use in naming the wrapper functions for the application's methods and properties. Also specify a prefix for the application's constants. The vlax-import-type-library function takes the following syntax:

(vlax-import-type-library :tlb-filename filename
[ :methods-prefix mprefix:properties-prefix pprefix :constants-prefix cprefix])

The filename argument is a string that names the type library. If you do not specify a path, AutoCAD looks for the file in the support file search path.

The mprefix argument specifies the prefix to be used for method wrapper functions. For example, if the type library contains a Calculate method and the mprefix parameter is set to "cc-", AutoCAD generates a wrapper function named cc-Calculate. This parameter defaults to "".

The pprefix argument specifies the prefix to be used for property wrapper functions, and the cprefix argument defines the prefix to be used for constants contained in the type library. These parameters also default to "".

Note the required use of keywords when passing arguments to vlax-import-type-library. For example, the following code imports a Microsoft Word type library, assigning the prefix mswm- to methods, mswp- to properties, and mswc- to constants:

(if (equal nil mswc-wd100Words) ; check for a WinWord constant
  (vlax-import-type-library
    :tlb-filename "c:/Microsoft Office/Office/msword8.olb"
    :methods-prefix "mswm-"
    :properties-prefix "mswp-"
    :constants-prefix "mswc-"
  )
)

After importing the type library, you can use the VLISP Apropos feature to list the ActiveX wrapper functions resulting from the import. For example, enter mswm in the Apropos Options dialog box and select the Match by Prefix option to list all Microsoft Word ActiveX methods.

Importing an application's type library enables you to use VLISP features such as Apropos on the application's properties and methods, but you can access the application even if you do not import its type library. See Using ActiveX without Importing a Type Library.

Topics in this section

  • Coding Hints for Using vlax-import-type-library


Coding Hints for Using vlax-import-type-library

Importing a Type Library
Importing a Type Library
Establishing a Connection to an Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications > Importing a Type Library >
Coding Hints for Using vlax-import-type-library

In AutoCAD, vlax-import-type-library is executed at runtime rather than at compiletime. The following practices are recommended when using vlax-import-type-library:

  • If you want your code to run on different machines, avoid specifying an absolute path in the tlb-filename parameter.
  • If possible, avoid using vlax-import-type-library from inside any AutoLISP expression (in other words, always call it from a top-level position).
  • In your AutoLISP source file, code the vlax-import-type-library call before any code that uses method or property wrappers or constants defined in the type library.


Establishing a Connection to an Application

Coding Hints for Using vlax-import-type-library
Using ActiveX to Interact with Other Applications
Coding a Sample Application
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications >
Establishing a Connection to an Application

If an instance of Microsoft Word is already running on your PC, use vlax-get-object to establish a connection to the application. For example, the following function call establishes a connection to a Microsoft Word application, and saves a pointer to the application in a variable named msw:

(setq msw (vlax-get-object "Word.Application"))

The vlax-create-object function creates a new instance of an application object. For example, if the return value from vlax-get-object is nil, indicating that the requested application does not exist, you can use vlax-create-object to start the application. The following call starts Microsoft Word and saves a pointer to the application in variable msw:

(setq msw (vlax-create-object "Word.Application"))

Alternatively, you can use vlax-get-or-create-object to access an application. This function attempts to connect to an existing instance of an application, and starts a new instance if it doesn't find one.

The application object does not appear until you make it visible. You make an object visible by setting its Visible property to TRUE. For example, the following call makes the Microsoft Word application visible:

(vla-put-visible msw :vlax-true)


Coding a Sample Application

Establishing a Connection to an Application
Using ActiveX to Interact with Other Applications
Using ActiveX without Importing a Type Library
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications >
Coding a Sample Application

After accessing the application object, the remaining AutoLISP code is specific to the application you're working with and the tasks you want to accomplish. For example, the following function call accesses the documents collection object in Microsoft Word:

(setq docs (vla-get-documents msw))

The following command creates a new Word document:

(setq doc (mswm-add docs))

The following procedure creates an ActiveX application that works with Microsoft Word 97 and an AutoCAD drawing that contains mtext.

To copy mtext from an AutoCAD drawing into a Microsoft Word document

  1. Issue the following command to ensure that AutoLISP ActiveX support is loaded:
    (vl-load-com)
  2. Obtain the AutoCAD application and current ModelSpace objects and save their pointers:
    (setq *AcadApp* (vlax-get-acad-object))    ; Get AutoCAD application
    (setq *ModelSpace* (vla-get-ModelSpace
      (vla-get-ActiveDocument *AcadApp*)))     ; Get model space
  3. Import the Microsoft Word type library. Change the :tlb-filename argument in the following code to point to the msword8.olb file on your system, then run the code:
    (if (equal nil mswc-wd100Words) ; check for a Word constant
      (vlax-import-type-library
        :tlb-filename "c:/Microsoft Office/Office/msword8.olb"
        :methods-prefix "mswm-"
        :properties-prefix "mswp-"
        :constants-prefix "mswc-"
      )
    )

    This code first checks to see if a known Microsoft Word constant is defined with a value. If the constant has a value, it is assumed that the Word type library has already been imported and no further action is necessary. If the constant is nil, vlax-import-type-library is invoked.

  4. Establish a connection to a Microsoft Word application by running the following code:
    (setq msw (vlax-get-object "Word.Application.8"))
     (if (equal nil msw)
       (progn
         ; Word is not running. Start it.
         (setq msw (vlax-create-object "Word.Application.8"))
         (vla-put-visible msw :vlax-true)
       )
     )

    The code issues vlax-get-object to establish a connection to a running Microsoft Word application. (In this example, version 8—Word 97—is specified; if the 8 were omitted, any instance of Word would be accepted.) If there is no running instance of Word, vlax-create-object is issued to start one.

  5. The remaining code follows. Comments in the code explain the processing.
    (if (/= nil msw)
      (progn
        ;; Get the document collection object.
        (setq docs (vla-get-documents msw))
        ;; Add a new document
        (setq doc (mswm-add docs))
        ;; Get the paragraphs of the document (to do some formatting)
        (setq paragraphs (mswp-get-paragraphs doc))
        ;; Now iterate through the model space and export any mtext
        ;; every Mtext entity to Word.
        (vlax-for ent *ModelSpace*
          (if (equal (vla-get-ObjectName ent) "AcDbMText")
            (progn
               ;; Get the following information from the Mtext entity:
               ;;     o the text string
               ;;     o the location of a corner of the text boundary
               (setq text (vla-get-TextString ent)
                     textpos (vla-get-InsertionPoint ent)
                     arrayTextpos (vlax-variant-value textpos)
                     textinfo
                      (strcat
                     (rtos (vlax-safearray-get-element arrayTextpos 0) 2 2)
                    ", "
                     (rtos (vlax-safearray-get-element arrayTextpos 1) 2 2)
                    ", "
                    (rtos (vlax-safearray-get-element arrayTextpos 2) 2 2)
                      )
               ) ;_ end of setq
             ; Print some info (with formatting)
             ;  Get the last paragraph in the document
             (setq pg (mswp-get-last paragraphs))
             ;  Obtain the range of the paragraph
             (setq range (mswp-get-range pg))
             ;  Do some formatting
             (mswp-put-bold range 1)                       ;bold
             (mswp-put-underline range mswc-wdUnderlineSingle) ;underline
             ; 4) Insert info about the text at the end of the paragraph
             (mswm-InsertAfter range
                (strcat "AcDbMText at position " textinfo "\n"))
             ; Now show the text string (from the ACAD text entity)
             (setq pg (mswp-get-last paragraphs))
             (setq range (mswp-get-range pg))
             (mswp-put-bold range 0)
             (mswp-put-underline range mswc-wdUnderlineNone)
             (mswm-InsertAfter range (strcat text "\n\n"))
            ) ;_ end of progn
          ) ;_ end of if AcDbMText
        ) ;_ end of vlax-for
      ) ;_ end of progn
      (princ "\nNo Microsoft Word application found.\n")
    )
    Load and
run the code and look at the result in Microsoft Word.


Using ActiveX without Importing a Type Library

Coding a Sample Application
Using ActiveX to Interact with Other Applications
Calling an ActiveX Method with vlax-invoke-methodvlax-invoke-method functioncalling ActiveX methodsActiveX:methodsActiveX:interacting with other applications:calling ActiveX methods with vlax-invoke-method
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications >
Using ActiveX without Importing a Type Library

Importing an application type library and using the resulting ActiveX wrapper functions is convenient and provides access to VLISP features such as Apropos, but it comes at a cost. Applications such as Microsoft Word and Microsoft Excel contain hundreds of methods and properties, and creating wrappers for each of these adds up to significant memory usage. Also, you may need to use an ActiveX property or method for which there is no generated AutoLISP wrapper function. In this instance, and to avoid the overhead involved in importing a type library, VLISP provides the following AutoLISP functions:

  • vlax-invoke-method
  • vlax-get-property
  • vlax-put-property

Topics in this section

  • Calling an ActiveX Method with vlax-invoke-method
  • Obtaining an ActiveX Property with vlax-get-property
  • Updating an ActiveX Property with vlax-put-property


Calling an ActiveX Method with vlax-invoke-method

Using ActiveX without Importing a Type Library
Using ActiveX without Importing a Type Library
Obtaining an ActiveX Property with vlax-get-property
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications > Using ActiveX without Importing a Type Library >
Calling an ActiveX Method with vlax-invoke-method

The vlax-invoke-method function calls an ActiveX method directly. The function requires the following arguments:

  • The VLA-object the method is to work on
  • A symbol or string naming the method to be called
  • One or more arguments to be passed to the method

The return value from vlax-invoke-method depends on the method being invoked.

For example, the following invokes the AddCircle method to draw a circle in the model space (represented by the mspace variable) of the current AutoCAD drawing:

_$ (setq mycircle
     (vlax-invoke-method
mspace 'AddCircle circCenter 3.0))
#<VLA-OBJECT IAcadCircle 00bfd6e4>

In this example, circCenter is a variant (containing a three-element array of doubles) identifying the center of the circle, and 3.0 is the radius of the circle. The method returns a VLA-object, the circle drawn.


Obtaining an ActiveX Property with vlax-get-property

Calling an ActiveX Method with vlax-invoke-methodvlax-invoke-method functioncalling ActiveX methodsActiveX:methodsActiveX:interacting with other applications:calling ActiveX methods with vlax-invoke-method
Using ActiveX without Importing a Type Library
Updating an ActiveX Property with vlax-put-property
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications > Using ActiveX without Importing a Type Library >
Obtaining an ActiveX Property with vlax-get-property

The vlax-get-property function returns the property of an object. The function requires the following arguments:

  • A VLA-object identifying the object whose property you are interested in
  • A symbol or string naming the property to be retrieved

For example, there is no wrapper function available to obtain the CommandBars property of an Microsoft Word application object, but the following command achieves this:

_$ (setq ComBars (vlax-get-property
msw 'CommandBars))
#<VLA-OBJECT CommandBars 0016763c>

You can use vlax-get-property (and vlax-invoke-method and vlax-put-property) even if a wrapper function is available for the task. For example, the following returns the AutoCAD's ActiveDocument property:

_$ (vlax-get-property
acadObject 'ActiveDocument)
#<VLA-OBJECT IAcadDocument 00302a18>

In this instance, you could have instead used vla-get-ActiveDocument to obtain the ActiveDocument property.


Updating an ActiveX Property with vlax-put-property

Obtaining an ActiveX Property with vlax-get-property
Using ActiveX without Importing a Type Library
Advanced Topics
AutoLISP Developer's Guide > Using the Visual LISP Environment > Working with ActiveX > Using ActiveX to Interact with Other Applications > Using ActiveX without Importing a Type Library >
Updating an ActiveX Property with vlax-put-property

The vlax-put-property function updates the property of an object. The function requires the following arguments:

  • A VLA-object identifying the object whose property you are updating
  • A symbol or string naming the property to be set
  • The value to set the property to

If vlax-put-property updates the property successfully, it returns nil.

The following function call changes the size of the Microsoft Word toolbar buttons by updating the LargeButtons property of the CommandBars object:

_$ (vlax-put-property
combars 'LargeButtons :vlax-true)
nil


Advanced Topics

Updating an ActiveX Property with vlax-put-property
Using the Visual LISP Environment
Attaching Reactors to AutoCAD Drawings
AutoLISP Developer's Guide > Using the Visual LISP Environment >
Advanced Topics

You can use reactors for event notification.

Visual LISP® not only makes program development easier and faster, it also provides new functionality to LISP applications. For example, you can attach reactors to entities in the AutoCAD® drawing window, allowing your application to respond to user actions on these entities.

Topics in this section

  • Attaching Reactors to AutoCAD Drawings


Attaching Reactors to AutoCAD Drawings

Advanced Topics
Advanced Topics
Understanding Reactor Types and Events
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics >
Attaching Reactors to AutoCAD Drawings

A reactor is an object you attach to AutoCAD drawing objects to have AutoCAD notify your application when events you are interested in occur. For example, if a user moves an entity that your application has attached a reactor to, your application will receive notification that the entity has moved. If you design it to do so, your application can react to this notification with appropriate actions, such as moving other entities associated with the one moved, or perhaps updating a text tag that records revision information on the altered drawing feature.

A reactor communicates with your application by calling a function you have associated with the reactor. Such a function is referred to as a callback function. There isn't anything particularly unusual about reactor callback functions—they are like other functions you write with VLISP. They become callback functions when you attach them to reactor events.

Before you can use reactor functions with AutoLISP, you must load the supporting code that enables these functions. Issue the following function call to load reactor support:

vl-load-com

This function first checks whether reactor support is already loaded; if reactor support is loaded, the function does nothing, otherwise, it loads reactor support and other AutoLISP extended functions.

NoteAll applications that use reactors—including all callback functions—should begin by calling vl-load-com.

Topics in this section

  • Understanding Reactor Types and Events
  • Defining Callback Functions
  • Creating Reactors
  • Working with Reactors in Multiple Namespaces
  • Querying, Modifying, and Removing Reactors
  • Transient versus Persistent Reactors
  • Reactor Use Guidelines


Understanding Reactor Types and Events

Attaching Reactors to AutoCAD Drawings
Attaching Reactors to AutoCAD Drawings
Reactor Callback Events
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Understanding Reactor Types and Events

There are many types of AutoCAD reactors. Each reactor type responds to one or more AutoCAD events. The different types of reactors are grouped into the following categories:

Database Reactors

Database reactors notify your application when specific events occur to the drawing database, such as when an object has been added to the database.

Document Reactors

Document reactors notify your application of a change to the current drawing document, such as opening a new drawing document, activating a different document window, and changing a document's lock status.

Editor Reactors

Editor reactors notify you each time an AutoCAD command is invoked; a drawing opens, closes, or is saved; a DXF file is imported or exported; or a system variable changes value.

Linker Reactors

Linker reactors notify your application every time an ObjectARX application is loaded or unloaded.

Object Reactors

Object reactors notify you each time a specific object is changed, copied, or deleted.

With the exception of Editor reactors, there is one type of reactor for each reactor category. The following table lists the name by which each reactor type is identified in AutoLISP code:

General reactor types
Reactor type identifier | Description
:VLR-AcDb-Reactor | Database reactor
:VLR-DocManager-Reactor | Document management reactor
:VLR-Editor-Reactor | General Editor reactor—maintained for backward-compatibility
:VLR-Linker-Reactor | Linker reactor
:VLR-Object-Reactor | Object reactor

Beginning with AutoCAD 2000, the broad class of Editor reactors is broken down into more specific reactor types. The :VLR-Editor-Reactor type is retained for backward-compatibility, but any new Editor reactors introduced with AutoCAD 2000 cannot be referenced through :VLR-Editor-Reactor. The following table lists the types of Editor reactors available beginning with AutoCAD 2000.

Editor reactor types
Reactor type | Description
:VLR-Command-Reactor | Provides notification of a command event
:VLR-DeepClone-Reactor | Provides notification of a deep clone event
:VLR-DWG-Reactor | Provides notification of a drawing event (for example, opening or closing a drawing file)
:VLR-DXF-Reactor | Provides notification of an event related to reading or writing of a DXF file
:VLR-Insert-Reactor | Provides notification of an event related to block insertion
:VLR-Lisp-Reactor | Provides notification of an AutoLISP event
:VLR-Miscellaneous-Reactor | Does not fall under any of the other editor reactor types
:VLR-Mouse-Reactor | Provides notification of a mouse event (for example, a double-click)
:VLR-SysVar-Reactor | Provides notification of a change to a system variable
:VLR-Toolbar-Reactor | Provides notification of a change to the bitmaps in a toolbar
:VLR-Undo-Reactor | Provides notification of an undo event
:VLR-Wblock-Reactor | Provides notification of an event related to writing a block
:VLR-Window-Reactor | Provides notification of an event related to moving or sizing an AutoCAD window
:VLR-XREF-Reactor | Provides notification of an event related to attaching or modifying xrefs

Use the vlr-types function to return the complete list of reactor types.

Topics in this section

  • Reactor Callback Events


Reactor Callback Events

Understanding Reactor Types and Events
Understanding Reactor Types and Events
Defining Callback Functions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Understanding Reactor Types and Events >
Reactor Callback Events

For each reactor type there are a number of events that can cause the reactor to notify your application. These events are known as callback events, because they cause the reactor to call a function you associate with the event. For example, when you issue the Save command to save a drawing, a :vlr-beginSave event occurs. When you complete the save process, a :vlr-saveComplete event occurs. In designing a reactor-based application, it is up to you to determine the events you are interested in, and to write the callback functions to be triggered when these events occur.

The vlr-reaction-names function returns a list of all available events for a given reactor type:

(vlr-reaction-names reactor type)

For example, the following command returns a list of all events related to Object reactors:

$ (vlr-reaction-names
:VLR-Object-Reactor)
(:VLR-cancelled :VLR-copied :VLR-erased :VLR-unerased :VLR-goodbye :VLR-openedForModify :VLR-modified :VLR-subObjModified :VLR-modifyUndone :VLR-modifiedXData :VLR-unappended :VLR-reappended :VLR-objectClosed)
NoteIf this or any other vlr-* command fails with a “no function definition” message, you may have forgotten to call vl-load-com, the function that loads AutoLISP reactor support functions.

You can print out a list of all available reactor events, sorted by reactor type, by loading and running the following code in VLISP:

(defun print-reactors-and-events ()
  (foreach rtype (vlr-types)
    (princ (strcat "\n" (vl-princ-to-string rtype)))
    (foreach rname (vlr-reaction-names rtype)
      (princ (strcat "\n\t" (vl-princ-to-string rname)))))
  (princ))

The AutoLISP Reference lists each event available for a reactor type. For each reactor type, you can find this information by looking up the description of the function you use to define a reactor of that type. These functions have the same name as the reactor type, minus the leading colon. For example, vlr-acdb-reactor creates a database reactor, vlr-toolbar-reactor creates a toolbar reactor, and so on.


Defining Callback Functions

Reactor Callback Events
Attaching Reactors to AutoCAD Drawings
Defining Object Reactor Callback Functions
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Defining Callback Functions

To add reactor functionality to your application, you first need to write a callback function that performs the tasks needed at the time of the reactor event. After you define a callback function, you link the function to an event by creating a reactor object.

A callback function is a regular AutoLISP function, which you define using defun. However, there are some restrictions on what you can do in a callback function. You cannot call AutoCAD commands using the command function. Also, to access drawing objects, you must use ActiveX® functions; entget and entmod are not allowed inside callback functions. See Reactor Use Guidelines for more information.

Callback functions for all reactors, other than Object reactors, must be defined to accept two arguments:

  • The first argument identifies the Reactor object that called the function.
  • The second argument is a list of parameters set by AutoCAD.

The following example shows a function named saveDrawingInfo, which displays file path and size information. This function will be attached to a DWG Editor reactor that will fire when an AutoCAD drawing is saved.

(defun saveDrawingInfo (calling-reactor commandInfo / dwgname filesize)
    (vl-load-com)
    (setq dwgname (cadr commandInfo)
        filesize (vl-file-size dwgname)
  )
  (alert (strcat "The file size of " dwgname " is "
                 (itoa filesize) " bytes."
          )
  )
  (princ)
)

In this example, the calling-reactor variable identifies the reactor that invoked the function. The function retrieves the drawing name from the commandInfo parameter, then uses the vl-file-size function to retrieve the size of the drawing. Finally, the function displays the information in an alert box in the AutoCAD window.

The parameters passed to a callback function depend on the type of event associated with the function. For example, saveDrawingInfo will be associated with a saveComplete event. This event indicates that a Save command has been completed. For saveComplete events, AutoCAD passes the callback function a string containing the name of the file the drawing was saved in. On the other hand, a callback function that reacts to changes to system variables (sysVarChanged event) receives a parameter list containing the name of a system variable (a string) and a flag indicating if the change was successful. You can find a list of events for each reactor type, and the parameters associated with each event, in the AutoLISP Reference. The events are listed under the description of the functions used to define each type of reactor.

AutoCAD comes with two predefined callback functions. You can use these functions when testing your reactors:

  • vlr-beep-reaction is a simple function that beeps your PC.
  • vlr-trace-reaction prints a list of arguments to the VLISP Trace window each time a reactor fires this callback function.

Topics in this section

  • Defining Object Reactor Callback Functions


Defining Object Reactor Callback Functions

Defining Callback Functions
Defining Callback Functions
Creating Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Defining Callback Functions >
Defining Object Reactor Callback Functions

Unlike other AutoCAD reactors, object reactors are attached to specific AutoCAD entities (objects). When you define an object reactor, you must identify the entity the reactor is to be attached to. So callback functions for object reactors must be defined to accept three arguments:

  • The first argument identifies the object that fired the notification.
  • The second argument identifies the Reactor object that called the function.
  • The third argument is a list of parameters specific to the callback condition.

For example, the following code defines a callback function named print-radius. This function can be used to print the radius of a circle:

(defun print-radius (notifier-object reactor-object parameter-list)
  (vl-load-com)
  (cond
    (
     (vlax-property-available-p
       notifier-object
       "Radius"
     )
     (princ "The radius is ")
     (princ (vla-get-radius notifier-object))
    )
  )
)

Note that the code uses the vlax-property-available-p function to verify that the drawing object that notified this function contains a radius property.


Creating Reactors

Defining Object Reactor Callback Functions
Attaching Reactors to AutoCAD Drawings
Using Object Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Creating Reactors

You link a callback function to an event when you create a reactor. There is an AutoLISP function for creating each type of reactor. These functions have the same name as the reactor type, minus the leading colon. For example, vlr-acdb-reactor creates a database reactor, vlr-toolbar-reactor creates a toolbar reactor, and so on. Except for object reactors, the reactor creation functions require the following arguments:

  • AutoLISP data to be associated with the Reactor object
  • A list of pairs naming the event and the callback function to be associated with that event (event-name . callback_function)

For example, the following command defines a DWG Editor reactor. The reactor will invoke the saveDrawingInfo function in response to a user issuing a SAVE command:

(vlr-dwg-Reactor nil '((:vlr-saveComplete . saveDrawingInfo)))

In this example, the first argument is nil because there is no application-specific data to attach to this reactor. The second argument is a list consisting of dotted pair lists. Each dotted pair list identifies an event the reactor is to be notified about, and the callback function to be run in response to that event. In this case the reactor is notified of only one event, :vlr-saveComplete.

Editor reactors are notified each time the user issues a command, whether through the AutoCAD command line, a menu, a toolbar, or an AutoLISP program. So, the callback function for this DWG reactor needs to determine precisely what it is responding to. In the current example, save-drawingInfo simply checks for the Save command.

Possible events for each reactor type are listed in the AutoLISP Reference. To find the list of events for a reactor, refer to the entry in the AutoLISP Reference that describes the function used to create the reactor. For example, to find the list of possible events for a DWG reactor, refer to the entry for vlr-DWG-reactor.

All reactor construction functions return a Reactor object.

Topics in this section

  • Using Object Reactors
  • Attaching Data to Reactor Objects


Using Object Reactors

Creating Reactors
Creating Reactors
Attaching Data to Reactor Objects
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Creating Reactors >
Using Object Reactors

Unlike other AutoCAD reactors, object reactors are attached to specific AutoCAD entities (objects). When you define an object reactor, you must identify the entity to which the reactor is to be attached. The vlr-object-reactor function, which creates object reactors, requires the following arguments:

  • A list of VLA-objects identifying the drawing objects that are to fire notifications to the reactor. These objects are referred to as the reactor owners.
  • AutoLISP data to be associated with the Reactor object.
  • A list of pairs naming the event and the callback function to be associated with that event (event-name . callback_function).
WarningYou cannot modify an object in a callback function if it is included in the object reactor's owner list. Attempts to do so will generate an error message and can cause AutoCAD to fail.

For example, the following statement defines an object reactor with a single owner (the object identified by myCircle), then attaches the string “Circle Reactor” to the reactor and tells AutoCAD to invoke the print-radius function when a user modifies myCircle:

(setq circleReactor (vlr-object-reactor (list myCircle)
         "Circle Reactor" '((:vlr-modified . print-radius))))

The Reactor object is stored in variable circleReactor; you can refer to the reactor using this variable, as described in Querying, Modifying, and Removing Reactors.

When defining a list of owners, you must specify VLA-objects only; Ename objects are not allowed. VLA-objects are required because callback functions can only use ActiveX methods to modify AutoCAD objects, and ActiveX methods require a VLA-object to work on.

Note that, although you cannot use objects obtained through functions such as entlast and entget with callback reactors, you can convert these Ename objects into VLA-objects using the vlax-ename->vla-object function. See the AutoLISP Reference for more information on vlax-ename->vla-object.

To see how an object reactor works

  1. Load the following code to define a circle object; you will be prompted to draw the circle:
    (setq myCircle
       ; Prompt for the center
point and radius:
          (progn (setq ctrPt
             (getpoint "\nCircle center point: ")
                 radius (distance ctrPt
                          (getpoint ctrpt "\nRadius: ")
                        )
          )
       ; Add a circle to the
drawing model space. Nest the function
       ; calls to obtain the
path to the current drawing's model
       ; space: AcadObject >
ActiveDocument > ModelSpace
           (vla-addCircle
              (vla-get-ModelSpace
                 (vla-get-ActiveDocument (vlax-get-acad-object))
              )
            (vlax-3d-point ctrPt)
            radius
           )
        )
    )

    This code uses vla-addCircle to draw a circle, assigning the return value to variable myCircle. The return value is a VLA-object, which contains a pointer to the Circle object drawn.

  2. Load the print-radius callback function shown in Defining Object Reactor Callback Functions.
  3. Define the reactor with the following command:
    (setq circleReactor (vlr-object-reactor (list myCircle)
             "Circle Reactor" '((:vlr-modified . print-radius))))
  4. In the AutoCAD drawing window, select the circle and change its size. The print-radius function will display a message in the AutoCAD Command window. For example, if you use the STRETCH command to enlarge the circle, the message looks like the following:

    Specify stretch point or [Base point/Copy/Undo/eXit]: The radius is 3.75803


Attaching Data to Reactor Objects

Using Object Reactors
Creating Reactors
Working with Reactors in Multiple Namespaces
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Creating Reactors >
Attaching Data to Reactor Objects

The object reactor creation example in Using Object Reactors included a string, “Circle Reactor,” in the call to vlr-object-reactor. You do not have to specify any data to be included with the reactor; you can specify nil instead. However, an object may have several reactors attached to it. Include an identifying text string, or other data your application can use, to allow you to distinguish among the different reactors attached to an object.


Working with Reactors in Multiple Namespaces

Attaching Data to Reactor Objects
Attaching Reactors to AutoCAD Drawings
Querying, Modifying, and Removing Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Working with Reactors in Multiple Namespaces

The current implementation of AutoLISP supports working in one drawing document at a time. Some AutoCAD APIs, such as ObjectARX and VBA, do support the ability of an application to work simultaneously in multiple documents. As a result, an application may modify an open drawing that is not currently active. This is not supported in AutoLISP. (Note that a VLX may run in a separate-namespace from the document it is loaded from, but it is still associated with that document and cannot manipulate objects in another document.)

AutoLISP does provide limited support for reactor callback functions executing in a document that is not active. By default, a reactor callback function will execute only if a notification event occurs when the document it was defined in is the active document. You can alter this behavior using the vlr-set-notification function.

To specify that a reactor should execute its callback function even if the document it was defined in is not active (for example, if an application in another namespace triggers an event), issue the following function call:

(vlr-set-notification reactor-object 'all-documents)

To modify a reactor so it only executes its callback function if an event occurs when the document it was defined in is active, issue the following:

(vlr-set-notification reactor-object 'active-document-only)

The vlr-set-notification function returns the specified reactor object. For example, the following sequence of commands defines a reactor and sets it to respond to events whether or not its associated document is active:

_$ (setq circleReactor
(vlr-object-reactor (list myCircle)
"Circle Reactor"
'((:vlr-modified . print-radius))))
#<VLR-Object-Reactor>
_$ (vlr-set-notification
circleReactor 'all-documents)
#<VLR-Object-Reactor>

To determine the notification setting of a reactor, use the vlr-notification function. For example:

_$ (vlr-notification
circleReactor)
all-documents

The vlr-set-notification function affects only the specified reactor. All reactors are created with the default notification set to active-document-only.

WarningIf you choose to set a reactor to execute its callback function even if triggered when its document is not active, the callback function should do nothing other than set and read AutoLISP variables. Any other action may cause system instability.


Querying, Modifying, and Removing Reactors

Working with Reactors in Multiple Namespaces
Attaching Reactors to AutoCAD Drawings
Inspecting Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Querying, Modifying, and Removing Reactors

There are various ways to obtain information about reactors. VLISP supplies AutoLISP functions to query reactors, and you can use standard VLISP data inspection tools to view information on them.

To use AutoLISP to list all reactors in a drawing, call the vlr-reactors function. The function returns a list of reactor lists. Each reactor list begins with a symbol identifying the reactor type, followed by pointers to each reactor of that type. For example:

_$ (vlr-reactors)
((:VLR-Object-Reactor #<VLR-Object-Reactor>) (:VLR-Editor-Reactor #<VLR-Editor-Reactor>))

In this example, vlr-reactors returned a list containing two lists, one identifying a single object reactor and one identifying a single Editor reactor.

To list all reactors of a given type, supply vlr-reactors with an argument identifying the reactor type. Specify one of the values returned by the vlr-types function; these are listed in “Understanding Reactor Types and Events”. For example, the following lists all DWG reactors:

_$ (vlr-reactors
:vlr-dwg-reactor)
((:VLR-DWG-Reactor #<VLR-DWG-Reactor> #<VLR-DWG-Reactor>))

In this case, the return value is a list containing one list. The one list identifies pointers to two DWG reactors.

Topics in this section

  • Inspecting Reactors
  • Querying Reactors Using Function Calls
  • Modifying Reactors
  • Removing Reactors


Inspecting Reactors

Querying, Modifying, and Removing Reactors
Querying, Modifying, and Removing Reactors
Querying Reactors Using Function Calls
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Querying, Modifying, and Removing Reactors >
Inspecting Reactors

You can examine reactors using the VLISP Inspect tool. For example, the object reactor defined in Using Object Reactors was returned to the variable circleReactor. If you open an Inspect window for this variable, VLISP displays the following information:

The list items in the Inspect window show the following:

  • Objects owning the reactor
  • Event and associated callback function
  • Whether or not the reactor is active (yes if added-p is T, no if added-p is nil)
  • User data attached to the reactor
  • Document range in which the reactor will fire (if 0, it fires only in the context of the drawing document it was created in; if 1, the reactor responds in the context of any document (see Working with Reactors in Multiple Namespaces for more information on this topic))
  • The AutoCAD document attached to the object reactor

Double-click on the item that begins with {Owners} to view a list of the owner objects:

Double-click on a list item to obtain detailed information about an owner.


Querying Reactors Using Function Calls

Inspecting Reactors
Querying, Modifying, and Removing Reactors
Modifying Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Querying, Modifying, and Removing Reactors >
Querying Reactors Using Function Calls

VLISP also provides functions to inspect a reactor definition from within an application program, or at the Console prompt:

  • vlr-type returns the type of the specified reactor. For example:

    $ (vlr-type circleReactor)

    :VLR-Object-Reactor

  • vlr-current-reaction-name returns the name of the event that caused the callback function to be called.
  • vlr-data returns the application-specific data value attached to the reactor, as shown in the following example:

    $ (vlr-data circleReactor)

    "Circle Reactor"

    You can use this data to distinguish among multiple reactors that can fire the same callback function.

  • vlr-owners returns a list of the objects in an AutoCAD drawing that fire notifications to an object reactor. The following function call lists the objects that fire notifications to circleReactor:

    _$ (vlr-owners circleReactor)

    (#<VLA-OBJECT IAcadCircle 03ad077c>)

  • vlr-reactions returns the callback list of condition-function pairs of the specified reactor. The following example returns information about circleReactor:

    $ (vlr-reactions circleReactor)

    ((:vlr-modified . PRINT-RADIUS))


Modifying Reactors

Querying Reactors Using Function Calls
Querying, Modifying, and Removing Reactors
Removing Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Querying, Modifying, and Removing Reactors >
Modifying Reactors

VLISP provides functions to modify reactor definitions:

  • vlr-reaction-set changes the callback function link for the specified reactor event. The function syntax is:

    (vlr-reaction-set reactor callback-condition 'callback-function)

    For example, the following command changes the circleReactor reactor to call the print-area function when an object is modified:

    $ (vlr-reaction-set circleReactor :vlr-modified 'print-area)

    PRINT-AREA

  • vlr-data-set changes the application-specific data associated with the reactor. For example, the following call replaces the text string used to identify the circleReactor reactor:

    $ (vlr-data-set circleReactor "Circle Area Reactor")

    "Circle Area Reactor"

    You can verify that the reactor has changed by using the VLISP Inspect feature. If the Inspect window shown in Inspecting Reactors is still displayed in your VLISP session, right-click in the window's object line and choose Update. If you've modified the circleReactor reactor as shown in this section, the updated Inspect window will look like the following:

  • vlr-owner-add adds a database object to the list of owners of the specified reactor. In the following example, an ARC object named archie is added to the owner list of reactor circleReactor:

    $ (vlr-owner-add circleReactor archie)

    #<VLA-OBJECT IAcadArc 03ad0bcc>

    Now, if a user modifies the archie object, the callback function defined for reactor circleReactor is invoked. You can verify this by inspecting the reactor. Update the Inspect window for the circleReactor reactor, then right-click on the list item that begins with {Owners} and choose Inspect:

    Both the Arc and Circle objects are listed in the Inspect window.

  • vlr-owner-remove removes an Owner object from the list of reactor owners. For example, the following command removes archie from the circleReactor owner list:

    $ (vlr-owner-remove circleReactor archie)

    #<VLA-OBJECT IAcadArc 03ad0bcc>


Removing Reactors

Modifying Reactors
Querying, Modifying, and Removing Reactors
Transient versus Persistent Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Querying, Modifying, and Removing Reactors >
Removing Reactors

Use the vlr-remove function to disable a reactor. Disabling the reactor does not delete it: the Reactor object still exists and you can activate it again using the vlr-add function. To determine whether or not a reactor is active (registered to AutoCAD), use the vlr-added-p function:

_$ (vlr-added-p circleReactor)
T

The vlr-added-p function returns T if the reactor is active, nil if it is not.

The following command disables reactor circleReactor:

_$ (vlr-remove circleReactor)
#<VLR-Object-reactor>

You can use vlr-added-p to verify the circleReactor object reactor has been disabled:

$ (vlr-added-p circleReactor)
nil

To enable the circleReactor reactor, use vlr-add:

$ (vlr-add circleReactor)
#<VLR-Object-reactor>

You can use the vlr-remove-all function to disable all reactors in your drawing. To disable all reactors of a particular type, specify the reactor type when calling vlr-remove-all. The following function call disables all object reactors:

$ (vlr-remove-all :vlr-object-reactor)
(#<VLR-Object-reactor>)


Transient versus Persistent Reactors

Removing Reactors
Attaching Reactors to AutoCAD Drawings
Opening a Drawing Containing Persistent Reactors
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Transient versus Persistent Reactors

Reactors may be transient or persistent. Transient reactors are lost when a drawing closes; this is the default reactor mode. Persistent reactors are saved with the drawing and exist when the drawing is next opened.

Use the vlr-pers function to make a reactor persistent. To remove persistence from a reactor and make it transient, use vlr-pers-release. Each function takes a Reactor object as its only argument. For example, the following command makes a reactor persistent:

_$ (vlr-pers circleReactor)
#<VLR-Object-Reactor>

If successful, vlr-pers returns the specified Reactor object.

To determine whether a Reactor object is persistent or transient, issue vlr-pers-p. For example:

_$ (vlr-pers-p circleReactor)
#<VLR-Object-Reactor>

The vlr-pers-p function returns the Reactor object if it is persistent, nil if it is not.

Topics in this section

  • Opening a Drawing Containing Persistent Reactors


Opening a Drawing Containing Persistent Reactors

Transient versus Persistent Reactors
Transient versus Persistent Reactors
Reactor Use Guidelines
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings > Transient versus Persistent Reactors >
Opening a Drawing Containing Persistent Reactors

A reactor is only a link between an event and a callback function. While this link remains, the callback function itself is not part of the reactor, and is normally not part of the drawing. The reactors saved in the drawing are only usable if their associated callback functions are loaded in AutoCAD. You can cause this to occur automatically when a drawing is opened if you define the reactor and callback functions in a separate-namespace VLX.

If you open a drawing containing VLISP reactor information and the associated callback functions are not loaded, AutoCAD displays an error message. You can use the vlr-pers-list function to return a list of all Persistent reactors in a drawing document.


Reactor Use Guidelines

Opening a Drawing Containing Persistent Reactors
Attaching Reactors to AutoCAD Drawings
Using the AutoLISP Language
AutoLISP Developer's Guide > Using the Visual LISP Environment > Advanced Topics > Attaching Reactors to AutoCAD Drawings >
Reactor Use Guidelines

When using reactors, try to adhere to the following guidelines. Reactors that violate these guidelines can result in unpredictable results for your application if the internal implementation of reactors changes.

  • Do not rely on the sequence of reactor notifications.

    It is recommended that, with a few exceptions, you do not rely on the sequence of reactor notifications. For example, an OPEN command triggers BeginCommand, BeginOpen, EndOpen, and EndCommand events. However, they may not occur in that order. The only event sequence you can safely rely on is that a Begin event will occur before the corresponding End event. For example, commandWillStart() always occurs before commandEnded(), and beginInsert() always occurs before endInsert(). Relying on more complex sequences may result in problems for your application if the sequence is changed as a result of new notifications being introduced in the future and existing ones being rearranged.

  • Do not rely on the sequence of function calls between notifications.

    It is not guaranteed that certain functions will be called between certain notifications. For example, when you receive :vlr-erased notification on object A, all it means is that object A is erased. If you receive :vlr-erased notification on A followed by a :vlr-erased notification on B, all it means is that both objects A and B are erased; it does not ensure that B was erased after A. If you tie your application to this level of detail, there is a very high probability of your application breaking in future releases. Instead of relying on sequences, rely on reactors to indicate the state of the system.

  • Do not use any interactive functions in your reactor callback function (for example, do not use getPoint, entsel).

    Attempting to execute interactive functions from within a reactor callback function can cause serious problems, as AutoCAD may still be processing a command at the time the event is triggered. Therefore, avoid the use of input-acquisition methods such as getPoint, entsel, and getkword, as well as selection set operations and the command function.

  • Do not launch a dialog box from within an event handler.

    Dialog boxes are considered interactive functions and can interfere with the current operation of AutoCAD. However, message boxes and alert boxes are not considered interactive and can be issued safely.

  • Do not update the object that issued the event notification.

    The event causing an object to trigger a callback function may still be in progress and the object still in use by AutoCAD when the callback function is invoked. Therefore, do not attempt to update an object from a callback function for the same object. You can, however, safely read information from the object triggering an event. For example, suppose you have a floor filled with tiles and you attach a reactor to the border of the floor. If you change the size of the floor, the reactor callback function will automatically add or subtract tiles to fill the new area. The function will be able to read the new area of the border, but it cannot attempt any changes on the border itself.

  • Do not perform any action from a callback function that will trigger the same event.

    If you perform an action in your reactor callback function that triggers the same event, you will create an infinite loop. For example, if you attempt to open a drawing from within a BeginOpen event, AutoCAD will simply continue to open more drawings until the maximum number of open drawings is reached.

  • Verify that a reactor is not already set before setting it, or you may end up with multiple callbacks on the same event.
  • Remember that no events will be fired while AutoCAD is displaying a modal dialog.


Using the AutoLISP Language

Reactor Use Guidelines
AutoLISP Basics
AutoLISP Developer's Guide >
Using the AutoLISP Language

Topics in this section

  • AutoLISP Basics

    You can use number, string, and list-handling functions to customize AutoCAD.

  • Using AutoLISP to Communicate with AutoCAD

    Query and command functions provide direct access to AutoCAD commands and drawing services.

  • Using AutoLISP to Manipulate AutoCAD Objects

    You can select and handle objects, and use their extended data.


AutoLISP Basics

Using the AutoLISP Language
Using the AutoLISP Language
AutoLISP Expressions
AutoLISP Developer's Guide > Using the AutoLISP Language >
AutoLISP Basics

You can use number, string, and list-handling functions to customize AutoCAD.

This chapter introduces the basic concepts of the AutoLISP® programming language. It describes the core components and data types used in AutoLISP, and presents examples of simple number-, string-, output-, and list-handling functions.

AutoLISP code does not need to be compiled, so you can enter the code at a Command line and immediately see the results. Some examples in this chapter are intended to be entered at the Visual LISP® (VLISP) Console window prompt (_$), while others are entered at the AutoCAD® Command prompt (Command:).

Topics in this section

  • AutoLISP Expressions
  • AutoLISP Data Types
  • AutoLISP Program Files
  • AutoLISP Variables
  • Number Handling
  • String Handling
  • Basic Output Functions
  • Equality and Conditional
  • List Handling
  • Symbol and Function Handling
  • Error Handling in AutoLISP


AutoLISP Expressions

AutoLISP Basics
AutoLISP Basics
AutoLISP Function Syntax
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
AutoLISP Expressions

An AutoLISP program consists of a series of expressions. AutoLISP expressions have the following form:

(function arguments)

Each expression begins with an open (left) parenthesis and consists of a function name and optional arguments to that function. Each argument can also be an expression. The expression ends with a right parenthesis. Every expression returns a value that can be used by a surrounding expression. The value of the last interpreted expression is returned to the calling expression.

For example, the following code example involves three functions:

(fun1 (fun2 arguments)(fun3 arguments))

If you enter this code at the Visual LISP Console prompt or the AutoCAD Command prompt, the AutoCAD AutoLISP interpreter processes the code. The first function, fun1, has two arguments, and the other functions, fun2 and fun3, each have one argument. The functions fun2 and fun3 are surrounded by function fun1, so their return values are passed to fun1 as arguments. Function fun1 evaluates the two arguments and returns the value to the window from which you entered the code.

The following example shows the use of the * (multiplication) function, which accepts one or more numbers as arguments:

_$ (* 2 27)
54

Because this code example has no surrounding expression, AutoLISP returns the result to the window from which you entered the code.

Expressions nested within other expressions return their result to the surrounding expression. The following example uses the result from the + (addition) function as one of the arguments for the * (multiplication) function.

_$ (* 2 (+ 5 10))
30

If you enter the incorrect number of close (right) parentheses, AutoLISP displays the following prompt:

(_>

The number of open parentheses in this prompt indicates how many levels of open parentheses remain unclosed. If this prompt appears, you must enter the required number of close parentheses for the expression to be evaluated.

_$ (* 2 (+ 5 10
((_> ) )
30

A common mistake is to omit the closing quotation mark (") in a text string, in which case the close parentheses are interpreted as part of the string and have no effect in resolving the open parentheses. To correct this condition, press SHIFT + ESC to cancel the function, then re-enter it correctly.

Topics in this section

  • AutoLISP Function Syntax


AutoLISP Function Syntax

AutoLISP Expressions
AutoLISP Expressions
AutoLISP Data Types
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Expressions >
AutoLISP Function Syntax

In this guide, the following conventions describe the syntax for AutoLISP functions:

In this example, the foo function has one required argument, string, and one optional argument, number. Additional number arguments can be provided. Frequently, the name of the argument indicates the expected data type. The examples in the following table show both valid and invalid calls to the foo function.

Valid and invalid function call examples
Valid calls | Invalid calls
(foo "catch") | (foo 44 13)
(foo "catch" 22) | (foo "fi" "foe" 44 13)
(foo "catch" 22 31) | (foo)


AutoLISP Data Types

AutoLISP Function Syntax
AutoLISP Basics
Integers
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
AutoLISP Data Types

AutoLISP expressions are processed according to the order and data type of the code within the parentheses. Before you can fully utilize AutoLISP, you must understand the differences among the data types and how to use them.

Topics in this section

  • Integers
  • Reals
  • Strings
  • Lists
  • Selection Sets
  • Entity Names
  • VLA-objects
  • File Descriptors
  • Symbols and Variables


Integers

AutoLISP Data Types
AutoLISP Data Types
Reals
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Integers

Integers are whole numbers that do not contain a decimal point. AutoLISP integers are 32-bit signed numbers with values ranging from +2,147,483,647 to -2,147,483,648. (Note, however, that the getint function only accepts 16-bit numbers ranging from +32767 to -32678.) When you explicitly use an integer in an AutoLISP expression, that value is known as a constant. Numbers such as 2, -56, and 1,200,196 are valid AutoLISP integers.

If you enter a number that is greater than the maximum integer allowed (resulting in integer overflow), AutoLISP converts the integer to a real number. However, if you perform an arithmetic operation on two valid integers, and the result is greater than the maximum allowable integer, the resulting number will be invalid. The following examples illustrate how AutoLISP handles integer overflow.

The largest positive integer value retains its specified value:

_$ 2147483647
2147483647

If you enter an integer that is greater than the largest allowable value, AutoLISP returns the value as a real:

_$ 2147483648
2.14748e+009

An arithmetic operation involving two valid integers, but resulting in integer overflow, produces an invalid result:

_$ (+ 2147483646 3)
-2147483647

In this example the result is clearly invalid, as the addition of two positive numbers results in a negative number. But note how the following operation produces a valid result:

_$ (+ 2147483648 2)
2.14748e+009

In this instance, AutoLISP converts 2147483648 to a valid real before adding 2 to the number. The result is a valid real.

The largest negative integer value retains its specified value:

_$ -2147483647
-2147483647

If you enter a negative integer larger than the greatest allowable negative value, AutoLISP returns the value as a real:

_$ -2147483648
-2.14748e+009

The following operation concludes successfully, because AutoLISP first converts the overflow negative integer to a valid real:

_$ (- -2147483648 1)
-2.14748e+009


Reals

Integers
AutoLISP Data Types
Strings
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Reals

A real is a number containing a decimal point. Numbers between -1 and 1 must contain a leading zero. Real numbers are stored in double-precision floating-point format, providing at least 14 significant digits of precision. Note that VLISP does not show you all the significant digits.

Reals can be expressed in scientific notation, which has an optional e or E followed by the exponent of the number (for example, 0.0000041 is the same as 4.1e-6). Numbers such as 3.1, 0.23, -56.123, and 21,000,000.0 are valid AutoLISP reals.


Strings

Reals
AutoLISP Data Types
Lists
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Strings

A string is a group of characters surrounded by quotation marks. Within quoted strings the backslash (\) character allows control characters (or escape codes) to be included. When you explicitly use a quoted string in an AutoLISP expression, that value is known as a literal string or a string constant.

Examples of valid strings are “string 1” and “\nEnter first point:”.


Lists

Strings
AutoLISP Data Types
Selection Sets
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Lists

An AutoLISP list is a group of related values separated by spaces and enclosed in parentheses. Lists provide an efficient method of storing numerous related values. AutoCAD expresses 3D points as a list of three real numbers.

Examples of lists are (1.0 1.0 0.0), (“this” “that” “the other”), and (1 “ONE”).


Selection Sets

Lists
AutoLISP Data Types
Entity Names
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Selection Sets

Selection sets are groups of one or more objects (entities). You can interactively add objects to, or remove objects from, selection sets with AutoLISP routines.

The following example uses the ssget function to return a selection set containing all the objects in a drawing.

_$ (ssget "X")
<Selection set: 1>


Entity Names

Selection Sets
AutoLISP Data Types
VLA-objects
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Entity Names

An entity name is a numeric label assigned to objects in a drawing. It is actually a pointer into a file maintained by AutoCAD, and can be used to find the object's database record and its vectors (if they are displayed). This label can be referenced by AutoLISP functions to allow selection of objects for processing in various ways. Internally, AutoCAD refers to objects as entities.

The following example uses the entlast function to get the name of the last object entered into the drawing.

_$ (entlast)
<Entity name: 27f0540>

Entity names assigned to objects in a drawing are only in effect during the current editing session. The next time you open the drawing, AutoCAD assigns new entity names to the objects. You can use an object's handle to refer to it from one editing session to another; see Entity Handles and Their Uses for information on using handles.


VLA-objects

Entity Names
AutoLISP Data Types
File Descriptors
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
VLA-objects

Objects in a drawing can be represented as Visual LISP ActiveX® (VLA) objects, a data type introduced with Visual LISP. When working with ActiveX functions, you must refer to VLA-objects, not the ename pointer returned by functions such as entlast. For information on working with ActiveX objects, see Using ActiveX Objects with AutoLISP.


File Descriptors

VLA-objects
AutoLISP Data Types
Symbols and Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
File Descriptors

A file descriptor is a pointer to a file opened by the AutoLISP open function. The open function returns this pointer as an alphanumeric label. You supply the file descriptor as an argument to other AutoLISP functions that read or write to the file.

The following example opens the myinfo.dat file for reading. The open function returns the file descriptor:

_$ (setq file1 (open
"c:\\myinfo.dat" "r") )
#<file "c:\\myinfo.dat">

In this example, the file descriptor is stored in the file1 variable.

Files remain open until you explicitly close them in your AutoLISP program. The close function closes a file. The following code closes the file whose file descriptor is stored in the file1 variable:

_$ (close file1)
nil


Symbols and Variables

File Descriptors
AutoLISP Data Types
Protected Symbols
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types >
Symbols and Variables

AutoLISP uses symbols to refer to data. Symbol names are not case sensitive and may consist of any sequence of alphanumeric and notation characters, except the following:

Characters restricted from symbol names
( | (Open Parenthesis)
) | (Close Parenthesis)
. | (Period)
' | (Apostrophe)
" | (Quote Symbol)
; | (Semicolon)

A symbol name cannot consist only of numeric characters.

Technically, AutoLISP applications consist of either symbols or constant values, such as strings, reals, and integers. For the sake of clarity, this guide uses the term symbol to refer to a symbol name that stores static data, such as built-in and user-defined functions. The term variable is used to refer to a symbol name that stores program data. The following example uses the setq function to assign the string value "this is a string" to the str1 variable:

_$ (setq str1 "this
is a string")
"this is a string"

Help yourself and others who need to read your code. Choose meaningful names for your program symbols and variables.

Topics in this section

  • Protected Symbols


Protected Symbols

Symbols and Variables
Symbols and Variables
AutoLISP Program Files
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Data Types > Symbols and Variables >
Protected Symbols

You may be warned if you attempt to change the value of some symbols used by the AutoLISP language. These symbols are known as protected symbols, and include items such as arithmetic operators (for example, +, -) and the values T and nil. You can use the Visual LISP Symbol Service feature to determine if a symbol is protected.

When you first start AutoCAD, protected symbols receive no special protection. If you set a protected symbol at the AutoCAD Command prompt, you receive no indication that the symbol has any special status. However, once you start Visual LISP, this changes. From the moment you start Visual LISP until the end of your AutoCAD session, AutoLISP intercepts any attempt to modify a protected symbol. Processing of protected symbols depends on the status of a Visual LISP environment option. You can specify one of the following options:

  • Transparent Protected symbols are treated like any other symbol.
  • Print message AutoLISP issues a warning message when you modify a protected symbol but carries out the modification. For example, the following demonstrates what happens when you modify the symbol T:

    Command: (setq t "look out")

    ; *U* WARNING: assignment to protected symbol: T <- "look out"

    "look out"

  • Prompt to enter break loop This is the default option, resulting in AutoLISP displaying the following message box when you attempt to modify a protected symbol:

    If you choose No, the symbol's value is modified, and processing continues normally. If you choose Yes, processing is interrupted, and you enter a Visual LISP break loop. Control switches to the Visual LISP Console window. To set the symbol and continue processing, press the Continue button on the Visual LISP toolbar; to abort modification, press Reset.

  • Error This option prohibits modification of protected symbols. Any attempt to modify a protected symbol results in an error message.

To specify how AutoLISP responds to attempts to modify protected symbols, choose Tools [image] Environment Options [image] General Options from the Visual LISP menu.


AutoLISP Program Files

Protected Symbols
AutoLISP Basics
Formatting AutoLISP Code
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
AutoLISP Program Files

Although you can enter AutoLISP code in the Visual LISP Console window or at the AutoCAD Command prompt, testing and debugging a series of instructions are considerably easier when you save AutoLISP code in a file rather than re-entering it each time you make a refinement. AutoLISP source code is usually stored in ASCII text files with an .lsp extension. However, you can load AutoLISP code from any ASCII text file.

To create a new source file in VLISP, choose New File from the VLISP File menu.

To edit existing AutoLISP source code in VLISP, choose Open File from the VLISP File menu, and use the Open File dialog box to select your file. VLISP loads this file into its text editor and displays the contents in a new editor window.

Topics in this section

  • Formatting AutoLISP Code
  • Comments in AutoLISP Program Files
  • Color Coding


Formatting AutoLISP Code

AutoLISP Program Files
AutoLISP Program Files
Spaces in AutoLISP Code
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Program Files >
Formatting AutoLISP Code

The extensive use of parentheses in AutoLISP code can make it difficult to read. The traditional technique for combatting this confusion is indentation. The more deeply nested a line of code is, the farther to the right you position the line.

If you use the VLISP text editor to enter your code, VLISP automatically formats the code as you enter it. VLISP also has features to reformat a selection or an entire file. This improves the appearance of your code, making it more readable. For information on using these features, see Formatting Code with Visual LISP.

Topics in this section

  • Spaces in AutoLISP Code


Spaces in AutoLISP Code

Formatting AutoLISP Code
Formatting AutoLISP Code
Comments in AutoLISP Program Files
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Program Files > Formatting AutoLISP Code >
Spaces in AutoLISP Code

In AutoLISP, multiple spaces between variable names, constants, and function names are equivalent to a single space. The end of a line is also treated as a single space.

The following two expressions produce the same result:

(setq test1 123 test2 456)
(setq
    test1 123
    test2 456
)


Comments in AutoLISP Program Files

Spaces in AutoLISP Code
AutoLISP Program Files
Visual LISP Comment Styles
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Program Files >
Comments in AutoLISP Program Files

It is good practice to include comments in AutoLISP program files. Comments are useful to both the programmer and future users who may need to revise a program to suit their needs. Use comments to do the following:

  • Give a title, authorship, and creation date
  • Provide instructions on using a routine
  • Make explanatory notes throughout the body of a routine
  • Make notes to yourself during debugging

Comments begin with one or more semicolons (;) and continue through the end of the line.

; This entire line is a comment
(setq area (* pi r r))  ; Compute area of circle

Any text within ;| ... |; is ignored. Therefore, comments can be included within a line of code or extend for multiple lines. This type of comment is known as an in-line comment.

(setq tmode ;|some note here|; (getvar "tilemode"))

The following example shows a comment that continues for multiple lines:

(setvar "orthomode" 1) ;|comment starts here
and continues to this line,
but ends way down here|; (princ "\nORTHOMODE set On.")

It is recommended that you use comments liberally when writing AutoLISP programs. The tutorial files provided with VLISP contain good examples of commenting style. If you've installed the AutoLISP Tutorial files, you'll find the AutoLISP tutorial code in the Tutorial\VisualLISP directory.

Topics in this section

  • Visual LISP Comment Styles


Visual LISP Comment Styles

Comments in AutoLISP Program Files
Comments in AutoLISP Program Files
Color Coding
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Program Files > Comments in AutoLISP Program Files >
Visual LISP Comment Styles

The VLISP code formatter recognizes five types of comments and positions each comment according to its type. Refer to Applying Visual LISP Comment Styles for a description of each comment style.

Regardless of your commenting style, it is more important that comments be present rather than they obey any particular layout rules.


Color Coding

Visual LISP Comment Styles
AutoLISP Program Files
AutoLISP Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Program Files >
Color Coding

VLISP provides an additional solution to make AutoLISP text easier to read: color coding. VLISP looks at each word of text and tries to determine what type of AutoLISP language element the word represents (for example, a built-in function, a number, or a string). Every type of element is assigned its own color, so you can easily distinguish among them when viewing the code. See Understanding Visual LISP Color Coding for more information on the VLISP color coding feature.

Keep in mind that color coding is a VLISP text editor feature, and it is possible that someone who does not have access to VLISP may need to read your code some day. For this reason, you should still use indentation and alignment to enhance your program's readability.


AutoLISP Variables

Color Coding
AutoLISP Basics
Displaying the Value of a Variable
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
AutoLISP Variables

An AutoLISP variable assumes the data type of the value assigned to it. Until they are assigned new values, variables retain their original values. You use the AutoLISP setq function to assign values to variables.

(setq variable_name1 value1
[variable_name2 value2 ...])

The setq function assigns the specified value to the variable name given. It returns the value as its function result. If you issue setq at the Visual LISP Console prompt, the result is displayed in the Console window:

_$ (setq val 3
abc 3.875)
3.875
_$ (setq layr "EXTERIOR-WALLS")
"EXTERIOR-WALLS"
_$

Topics in this section

  • Displaying the Value of a Variable
  • Nil Variables
  • Predefined Variables


Displaying the Value of a Variable

AutoLISP Variables
AutoLISP Variables
Nil Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Variables >
Displaying the Value of a Variable

To display the current value of a variable when working in Visual LISP, just enter the variable name at the Console prompt as follows:

_$ abc
3.875

To display the value of a variable from the AutoCAD Command prompt, you must precede the variable name with an exclamation point (!). For example:

Command: !abc

3.875


Nil Variables

Displaying the Value of a Variable
AutoLISP Variables
Predefined Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Variables >
Nil Variables

An AutoLISP variable that has not been assigned a value is said to be nil. This is different from blank, which is considered a character string, and different from 0, which is a number. So, in addition to checking a variable for its current value, you can test to determine if the variable has been assigned a value.

Each variable consumes a small amount of memory, so it is good programming practice to reuse variable names or set variables to nil when their values are no longer needed. Setting a variable to nil releases the memory used to store that variable's value. If you no longer need the val variable, you can release its value from memory with the following expression:

_$ (setq val nil)
nil

Another efficient programming practice is to use local variables whenever possible. See Local Variables in Functions on this topic.


Predefined Variables

Nil Variables
AutoLISP Variables
Number Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > AutoLISP Variables >
Predefined Variables

The following predefined variables are commonly used in AutoLISP applications:

PAUSE

Defined as a string consisting of a double backslash (\\) character. This variable is used with the command function to pause for user input.

PI

Defined as the constant p (pi). It evaluates to approximately 3.14159.

T

Defined as the constant T. This is used as a non-nil value.

NoteYou can change the value of these variables with the setq function. However, other applications might rely on their values being consistent; therefore, it is recommended that you do not modify these variables. Visual LISP, by default, protects these variables from redefinition. You can override this protection through the VLISP Symbol Service feature or by setting a VLISP environment option.


Number Handling

Predefined Variables
AutoLISP Basics
String Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
Number Handling

AutoLISP provides functions for working with integers and real numbers. In addition to performing complex mathematical computations in applications, you can use the number-handling functions to help you in your daily use of AutoCAD. If you are drawing a steel connection detail that uses a 2.5" bolt that is 0.5" in diameter, how many threads are there if the bolt has 13 threads per inch? Use the * (multiplication) function at the Console prompt, as in the following example:

_$ (* 2.5 13)
32.5

The arithmetic functions that have a number argument (as opposed to num or angle, for example) return different values if you provide integers or reals as arguments. If all arguments are integers, the value returned is an integer. However, if one or all the arguments are reals, the value returned is a real. To ensure your application passes real values, be certain at least one argument is a real.

_$ (/ 12 5)
2
_$ (/ 12.0 5)
2.4

A complete list of number-handling functions is in AutoLISP Function Synopsis under the heading Arithmetic Functions These functions are described in the AutoLISP Reference.


String Handling

Number Handling
AutoLISP Basics
Basic Output Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
String Handling

AutoLISP provides functions for working with string values. For example, the strcase function returns the conversion of all alphabetic characters in a string to uppercase or lowercase. It accepts two arguments: a string and an optional argument that specifies the case in which the characters are returned. If the optional second argument is omitted, it evaluates to nil and strcase returns the characters converted to uppercase.

_$ (strcase "This is
a TEST.")
"THIS IS A TEST."

If you provide a second argument of T, the characters are returned as lowercase. AutoLISP provides the predefined variable T to use in similar situations where a non-nil value is used as a type of true/false toggle.

_$ (strcase "This is
a TEST." T)
"this is a test."

The strcat function combines multiple strings into a single string value. This is useful for placing a variable string within a constant string. The following code sets a variable to a string value and then uses strcat to insert that string into the middle of another string.

_$ (setq str "BIG")
(setq bigstr (strcat "This is a " str " test."))
"This is a BIG test."

If the variable bigstr is set to the preceding string value, you can use the strlen function to find out the number of characters (including spaces) in that string.

_$ (strlen bigstr)
19

The substr function returns a substring of a string. It has two required arguments and one optional argument. The first required argument is the string. The second argument is a positive integer that specifies the first character of the string you want to include in the substring. If the third argument is provided, it specifies the number of characters to include in the substring. If the third argument is not provided, substr returns all characters including and following the specified start character.

As an example, you can use the substr function to strip off the three-letter extension from a file name (note that you can actually use the vl-file-name-base function to do this). First, set a variable to a file name.

_$ (setq filnam "bigfile.txt")
"bigfile.txt"

You need to get a string that contains all characters except the last four (the period and the three-letter extension). Use strlen to get the length of the string and subtract 4 from that value. Then use substr to specify the first character of the substring and its length.

_$ (setq newlen (- (strlen
filnam) 4))
7
_$ (substr filnam 1
newlen)
"bigfile"

If your application has no need for the value of newlen, you can combine these two lines of code into one.

_$ (substr filnam 1
(- (strlen filnam) 4))
"bigfile"

Additional string-handling functions are listed in AutoLISP Function Synopsis under the heading String-Handling Functions These functions are described in the AutoLISP Reference.

AutoLISP also provides a number of functions that convert string values into numeric values and numeric values into string values. These functions are discussed in Conversions.


Basic Output Functions

String Handling
AutoLISP Basics
Displaying Messages
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
Basic Output Functions

AutoLISP includes functions for controlling the AutoCAD display, including both text and graphics windows. Some functions also display information in the Visual LISP Console window. The major text display functions are:

  • prin1
  • princ
  • print
  • prompt

These functions are discussed in the following sections. The remaining display functions are covered in Using AutoLISP to Communicate with AutoCAD, beginning with the Display Control topic.

Topics in this section

  • Displaying Messages
  • Control Characters in Strings
  • Wild-Card Matching


Displaying Messages

Basic Output Functions
Basic Output Functions
Exiting Quietly
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Basic Output Functions >
Displaying Messages

When entered from VLISP, the prompt function displays a message (a string) in the AutoCAD Command window and returns nil to the VLISP Console window. The princ, prin1, and print functions all display an expression (not necessarily a string) in the AutoCAD Command window and return the expression to the VLISP Console window. Optionally, these functions can send output to a file. The differences are as follows:

  • princ displays strings without the enclosing quotation marks.
  • prin1 displays strings enclosed in quotation marks.
  • print displays strings enclosed in quotation marks but places a blank line before the expression and a space afterward.

The following examples demonstrate the differences between the four basic output functions and how they handle the same string of text. If you enter the examples from VLISP, the text following prints is what you see at the AutoCAD Command prompt; text following returns appears within the VLISP Console window or within an application. See Control Characters in Strings for an explanation of the control characters used in the example.

(setq str "The \"allowable\" tolerance is \261 \274\"")
(prompt str)  printsThe "allowable" tolerance
is1/4"
and returns  nil
(princ str)   printsThe "allowable" tolerance
is1/4"
and returns  "The \"allowable\" tolerance is 1/4\""
(prin1 str)   prints"The \"allowable\"
tolerance is1/4""
and returns  "The \"allowable\" tolerance is  1/4\""
(print str)   prints<blank line>
"The \"allowable\"
tolerance is1/4""<space>
and returns  "The \"allowable\" tolerance is  1/4\""

Note that the write-char and write-line functions can also display output to a Command window. Refer to the AutoLISP Reference for information on these functions.

Topics in this section

  • Exiting Quietly


Exiting Quietly

Displaying Messages
Displaying Messages
Control Characters in Strings
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Basic Output Functions > Displaying Messages >
Exiting Quietly

If you invoke the princ function without passing an expression to it, it displays nothing and has no value to return. So if you write an AutoLISP expression that ends with a call to princ without any arguments, the ending nil is suppressed (because it has nothing to return). This practice is called exiting quietly.


Control Characters in Strings

Exiting Quietly
Basic Output Functions
Wild-Card Matching
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Basic Output Functions >
Control Characters in Strings

Within quoted strings, the backslash (\) character allows control characters (or escape codes) to be included. The following table shows the currently recognized control characters:

AutoLISP control characters
Code | Description
\\ | \ character
\" | " character
\e | Escape character
\n | Newline character
\r | Return character
\t | Tab character
\nnn | Character whose octal code is nnn

The prompt and princ functions expand the control characters in a string and display the expanded string in the AutoCAD Command window.

If you need to use the backslash character (\) or quotation mark (") within a quoted string, it must be preceded by the backslash character (\). For example, if you enter

_$ (princ "The \"filename\"
is: D:\\ACAD\\TEST.TXT. ")

the following text is displayed in the AutoCAD Command window:

The "filename" is: D:\ACAD\TEST.TXT

You will also see this output in the VLISP Console window, along with the return value from the princ function (which is your original input, with the unexpanded control characters).

To force a line break at a specific location in a string, use the newline character (\n).

_$ (prompt "An example
of the \nnewline character. ")
An example of the
newline character.

You can also use the terpri function to cause a line break.

The return character (\r) returns to the beginning of the current line. This is useful for displaying incremental information (for example, a counter showing the number of objects processed during a loop).

The Tab character (\t) can be used in strings to indent or to provide alignment with other tabbed text strings. In this example, note the use of the princ function to suppress the ending nil.

_$ (prompt "\nName\tOffice\n-
- - - -\t- - - - -
(_> \nSue\t101\nJoe\t102\nSam\t103\n")
(princ)
Name | Office
- - - - - | - - - - -
Sue | 101
Joe | 102
Sam | 103


Wild-Card Matching

Control Characters in Strings
Basic Output Functions
Equality and Conditional
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Basic Output Functions >
Wild-Card Matching

The wcmatch function enables applications to compare a string to a wild-card pattern. You can use this facility when you build a selection set (in conjunction with ssget) and when you retrieve extended entity data by application name (in conjunction with entget).

The wcmatch function compares a single string to a pattern. The function returns T if the string matches the pattern, and nil if it does not. The wild-card patterns are similar to the regular expressions used by many system and application programs. In the pattern, alphabetic characters and numerals are treated literally; brackets can be used to specify optional characters or a range of letters or digits; a question mark (?) matches a single character; an asterisk (*) matches a sequence of characters; and, certain other special characters have special meanings within the pattern. When you use the * character at the beginning and end of the search pattern, you can locate the desired portion anywhere in the string.

In the following examples, a string variable called matchme has been declared and initialized:

_$ (setq matchme "this
is a string - test1 test2 the end")
"this is a string - test1 test2 the end"

The following code checks whether or not matchme begins with the four characters "this":

_$ (wcmatch matchme
"this*")
T

The following code illustrates the use of brackets in the pattern. In this case, wcmatch returns T if matchme contains "test4", "test5", "test6" (4-6), or "test9" (note the use of the * character):

_$ (wcmatch matchme
"*test[4-69]*")
nil

In this case, wcmatch returns nil because matchme does not contain any of the strings indicated by the pattern.

However,

_$ (wcmatch matchme
"*test[4-61]*")
T

returns true because the string contains "test1".

The pattern string can specify multiple patterns, separated by commas. The following code returns T if matchme equals "ABC", or if it begins with "XYZ", or if it ends with "end".

_$ (wcmatch matchme
"ABC,XYZ*,*end")
T


Equality and Conditional

Wild-Card Matching
AutoLISP Basics
List Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
Equality and Conditional

AutoLISP includes functions that provide equality verification as well as conditional branching and looping. The equality and conditional functions are listed in AutoLISP Function Synopsis under the heading Equality and Conditional Functions These functions are described in the AutoLISP Reference.

When writing code that checks string and symbol table names, keep in mind that AutoLISP automatically converts symbol table names to upper case in some instances. When testing symbol names for equality, you need to make the comparison insensitive to the case of the names. Use the strcase function to convert strings to the same case before testing them for equality.


List Handling

Equality and Conditional
AutoLISP Basics
Point Lists
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
List Handling

AutoLISP provides functions for working with lists. This section provides examples of the append, assoc, car, cons, list, nth, and subst functions. A summary of all list-handling functions is in AutoLISP Function Synopsis under the heading List Manipulation Functions Each list-handling function is described in the AutoLISP Reference.

Lists provide an efficient and powerful method of storing numerous related values. After all, LISP is so-named because it is the LISt Processing language. Once you understand the power of lists, you'll find that you can create more powerful and flexible applications.

Several AutoLISP functions provide a basis for programming two-dimensional and three-dimensional graphics applications. These functions return point values in the form of a list.

The list function provides a simple method of grouping related items. These items do not need to be of similar data types. The following code groups three related items as a list:

_$ (setq lst1 (list
1.0 "One" 1))
(1.0 "One" 1)

You can retrieve a specific item from the list in the lst1 variable with the nth function. This function accepts two arguments. The first argument is an integer that specifies which item to return. A 0 specifies the first item in a list, 1 specifies the second item, and so on. The second argument is the list itself. The following code returns the second item in lst1.

_$ (nth 1 lst1)
"One"

The cdr function returns all elements, except the first, from a list. For example:

_$ (cdr lst1)
("One" 1)

The car function provides another way to extract items from a list. For more examples using car and cdr, and combinations of the two, see Point Lists.

Three functions let you modify an existing list. The append function returns a list with new items added to the end of it, and the cons function returns a list with new items added to the beginning of the list. The subst function returns a list with a new item substituted for every occurrence of an old item. These functions do not modify the original list; they return a modified list. To modify the original list, you must explicitly replace the old list with the new list.

The append function takes any number of lists and runs them together as one list. Therefore, all arguments to this function must be lists. The following code adds another "One" to the list lst1. Note the use of the quote (or ') function as an easy way to make the string "One" into a list.

_$ (setq lst2 (append
lst1 '("One")))
(1.0 "One" 1 "One")

The cons function combines a single element with a list. You can add another string "One" to the beginning of this new list, lst2, with the cons function.

_$ (setq lst3 (cons
"One" lst2 ))
("One" 1.0 "One" 1 "One")

You can substitute all occurrences of an item in a list with a new item with the subst function. The following code replaces all strings "One" with the string "one".

_$ (setq lst4 (subst
"one" "One" lst3))
("one" 1.0 "one" 1 "one")

Topics in this section

  • Point Lists
  • Dotted Pairs


Point Lists

List Handling
List Handling
Dotted Pairs
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > List Handling >
Point Lists

AutoLISP observes the following conventions for handling graphics coordinates. Points are expressed as lists of two or three numbers surrounded by parentheses.

2D points

Expressed as lists of two real numbers (X and Y, respectively), as in

(3.4 7.52)

3D points

Expressed as lists of three real numbers (X, Y, and Z, respectively), as in

(3.4 7.52 1.0)

You can use the list function to form point lists, as shown in the following examples:

_$  (list 3.875
1.23)
(3.875 1.23)
_$  (list 88.0 14.77 3.14)
(88.0 14.77 3.14)

To assign particular coordinates to a point variable, you can use one of the following expressions:

_$  (setq pt1 (list 3.875
1.23))
(3.875 1.23)
_$  (setq pt2 (list 88.0
14.77 3.14))
(88.0 14.77 3.14)
_$  (setq abc 3.45)
3.45
_$  (setq pt3 (list abc
1.23))
(3.45 1.23)

The latter uses the value of variable abc as the X component of the point.

If all members of a list are constant values, you can use the quote function to explicitly define the list, rather than the list function. The quote function returns an expression without evaluation, as follows:

_$ (setq pt1 (quote
(4.5 7.5)))
(4.5 7.5)

The single quotation mark (') can be used as shorthand for the quote function. The following code produces the same result as the preceding code.

_$ (setq pt1 '(4.5 7.5))
(4.5 7.5)

You can refer to X, Y, and Z components of a point individually, using three additional built-in functions called car, cadr, and caddr. The following examples show how to extract the X, Y, and Z coordinates from a 3D point list. The pt variable is set to the point (1.5 3.2 2.0):

_$ (setq pt '(1.5 3.2 2.0))
(1.5 3.2 2.0)

The car function returns the first member of a list. In this example it returns the X value of point pt to the x_val variable.

_$ (setq x_val (car
pt))
1.5

The cadr function returns the second member of a list. In this example it returns the Y value of the pt point to the y_val variable.

_$ (setq y_val (cadr
pt))
3.2

The caddr function returns the third member of a list. In this example it returns the Z value of point pt to the variable z_val.

_$ (setq z_val (caddr
pt))
2.0

You can use the following code to define the lower-left and upper-right (pt1 and pt2) corners of a rectangle, as follows:

_$ (setq pt1 '(1.0 2.0)
pt2 ' (3.0 4.0))
(3.0 4.0)

You can use the car and cadr functions to set the pt3 variable to the upper-left corner of the rectangle, by extracting the X component of pt1 and the Y component of pt2, as follows:

_$ (setq pt3 (list (car
pt1) (cadr pt2)))
(1.0 4.0)

The preceding expression sets pt3 equal to point (1.0,4.0).

AutoLISP supports concatenations of car and cdr up to four levels deep. The following are valid functions:

caaaar | cadaar | cdaaar | cddaar
caaadr | cadadr | cdaadr | cddadr
caaar | cadar | cdaar | cddar
caadar | caddar | cdadar | cdddar
caaddr | cadddr | cdaddr | cddddr
caadr | caddr | cdadr | cdddr
caar | cadr | cdar | cddr

These concatenations are the equivalent of nested calls to car and cdr. Each a represents a call to car, and each d represents a call to cdr. For example:

(caar x)    is equivalent
to  (car (car x))
(cdar x)    is equivalent
to  (cdr (car x))
(cadar x)   is equivalent
to  (car (cdr (car x)))
(cadr x)    is equivalent
to  (car (cdr x))
(cddr x)    is equivalent
to  (cdr (cdr x))
(caddr x)   is equivalent to  (car (cdr (cdr x)))


Dotted Pairs

Point Lists
List Handling
Symbol and Function Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > List Handling >
Dotted Pairs

Another way AutoLISP uses lists to organize data is with a special type of list called a dotted pair. This list must always contain two members. When representing a dotted pair, AutoLISP separates the members of the list with a period (.). Most list-handling functions will not accept a dotted pair as an argument, so you should be sure you are passing the right kind of list to a function.

Dotted pairs are an example of an "improper list." An improper list is one in which the last cdr is not nil. In addition to adding an item to the beginning of a list, the cons function can create a dotted pair. If the second argument to the cons function is anything other than another list or nil, it creates a dotted pair.

_$ (setq sublist (cons
'lyr "WALLS"))
(LYR . "WALLS")

The car, cdr, and assoc functions are useful for handling dotted pairs. The following code creates an association list, which is a list of lists, and is the method AutoLISP uses to maintain entity definition data. (Entity definition data is discussed in Using AutoLISP to Manipulate AutoCAD Objects) The following code creates an association list of dotted pairs:

_$ (setq wallinfo (list
sublist(cons 'len 240.0) (cons 'hgt 96.0)))
( (LYR . "WALLS")  (LEN . 240.0)  (HGT . 96.0) )

The assoc function returns a specified list from within an association list regardless of the specified list's location within the association list. The assoc function searches for a specified key element in the lists, as follows:

_$  (assoc 'len wallinfo)
(LEN  .  240.0)
_$  (cdr (assoc 'lyr
wallinfo))
"WALLS"
_$  (nth 1 wallinfo)
(LEN  .  240.0)
_$  (car (nth 1 wallinfo))
LEN


Symbol and Function Handling

Dotted Pairs
AutoLISP Basics
Using defun to Define a Function
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
Symbol and Function Handling

AutoLISP provides a number of functions for handling symbols and variables. The symbol-handling functions are listed in AutoLISP Function Synopsis under the heading Symbol-Handling Functions Each symbol-handling function is described in the AutoLISP Reference.

AutoLISP provides functions for handling one or more groups of functions. This section provides examples of the defun function. The remaining function-handling functions are listed in AutoLISP Function Synopsis under the heading Symbol-Handling Functions The functions are described in the AutoLISP Reference.

Topics in this section

  • Using defun to Define a Function
  • C:XXX Functions
  • Local Variables in Functions
  • Functions with Arguments


Using defun to Define a Function

Symbol and Function Handling
Symbol and Function Handling
Compatibility of defun with Previous Versions of AutoCAD
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling >
Using defun to Define a Function

With AutoLISP, you can define your own functions. Once defined, these functions can be used at the AutoCAD Command prompt, the Visual LISP Console prompt, or within other AutoLISP expressions, just as you use the standard functions. You can also create your own AutoCAD commands, because commands are just a special type of function.

The defun function combines a group of expressions into a function or command. This function requires at least three arguments, the first of which is the name of the function (symbol name) to define. The second argument is the argument list (a list of arguments and local variables used by the function). The argument list can be nil or an empty list (). Argument lists are discussed in greater detail in Functions with Arguments. If local variables are provided, they are separated from the arguments by a slash (/). Local variables are discussed in Local Variables in Functions. Following these arguments are the expressions that make up the function; there must be at least one expression in a function definition.

(defun symbol_name ( args / local_variables )
expressions
)

The following code defines a simple function that accepts no arguments and displays “bye” in the AutoCAD Command window. Note that the argument list is defined as an empty list (()):

_$ (defun DONE ( ) (prompt
"\nbye! "))
DONE

Now that the DONE function is defined, you can use it as you would any other function. For example, the following code prints a message, then says “bye” in the AutoCAD Command window:

_$ (prompt "The value
is 127.") (DONE) (princ)
The value is 127
bye!

Note how the previous example invokes the princ function without any arguments. This suppresses an ending nil and achieves a quiet exit.

Functions that accept no arguments may seem useless. However, you might use this type of function to query the state of certain system variables or conditions and to return a value that indicates those values.

AutoCAD can automatically load your functions each time you start a new AutoCAD session or open a new AutoCAD drawing file; see Automatically Load and Execute VBA Projects in the AutoCAD Customization Guide for further information on automatic loading.

Any code in an AutoLISP program file that is not part of a defun statement is executed when that file is loaded. You can use this to set up certain parameters or to perform any other initialization procedures in addition to displaying textual information, such as how to invoke the loaded function.

Topics in this section

  • Compatibility of defun with Previous Versions of AutoCAD


Compatibility of defun with Previous Versions of AutoCAD

Using defun to Define a Function
Using defun to Define a Function
C:XXX Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling > Using defun to Define a Function >
Compatibility of defun with Previous Versions of AutoCAD

The internal implementation of defun changed in AutoCAD 2000. This change will be transparent to the great majority of AutoLISP users upgrading from earlier versions of AutoCAD. The change only affects AutoLISP code that manipulated defun definitions as a list structure, such as by appending one function to another, as in the following code:

(append s::startup (cdr mystartup))

For situations like this, you can use defun-q to define your functions. An attempt to use a defun function as a list results in an error. The following example illustrates the error:

_$ (defun foo (x) 4)
foo
_$ (append foo '(3 4))
; error: Invalid attempt to access a compiled function definition.
You may want to define it using defun-q: #<SUBR @024bda3c FOO>

The error message alerts you to the possibility of using defun-q instead of defun.

The defun-q function is provided strictly for backward compatibility with previous versions of AutoLISP and should not be used for other purposes. For more information on using defun-q, and the related defun-q-list-set and defun-q-list-ref functions, see the AutoLISP Reference.


C:XXX Functions

Compatibility of defun with Previous Versions of AutoCAD
Symbol and Function Handling
Adding Commands
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling >
C:XXX Functions

If an AutoLISP function is defined with a name of the form C:xxx, it can be issued at the AutoCAD Command prompt in the same manner as a built-in AutoCAD command. This is true regardless of whether you define and load the function in VLISP or at the AutoCAD Command prompt. You can use this feature to add new commands to AutoCAD or to redefine existing commands.

To use functions as AutoCAD commands, be sure they adhere to the following rules:

  • The function name must use the form C:XXX (upper- or lowercase characters). The C: portion of the name must always be present; the XXX portion is a command name of your choice. C:XXX functions can be used to override built-in AutoCAD commands. (See Redefining AutoCAD Commands.)
  • The function must be defined with no arguments. However, local variables are permitted and it is a good programming practice to use them.

A function defined in this manner can be issued transparently from within any prompt of any built-in AutoCAD command, provided the function issued transparently does not call the command function. (This is the AutoLISP function you use to issue AutoCAD commands; see the entry on command in the AutoLISP Reference.) When issuing a C:XXX defined command transparently, you must precede the XXX portion with a single quotation mark (').

You can issue a built-in command transparently while a C:XXX command is active by preceding it with a single quotation mark ('), as you would with all commands that are issued transparently. However, you cannot issue a C:XXXcommand transparently while a C:XXX command is active.

NoteWhen calling a function defined as a command from the code of another AutoLISP function, you must use the whole name, including the parentheses; for example, (C:HELLO). You also must use the whole name and the parentheses when you invoke the function from the VLISP Console prompt.

Topics in this section

  • Adding Commands
  • Redefining AutoCAD Commands


Adding Commands

C:XXX Functions
C:XXX Functions
Redefining AutoCAD Commands
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling > C:XXX Functions >
Adding Commands

Using the C:XXX feature, you can define a command that displays a simple message.

_$ (defun C:HELLO ()
(princ "Hello world. \n") (princ))
C:HELLO

HELLO is now defined as a command, in addition to being an AutoLISP function. This means you can issue the command from the AutoCAD Command prompt.

Command: hello

Hello world.

This new command can be issued transparently because it does not call the command function itself. At the AutoCAD Command prompt, you could do the following:

Command: line

From point: 'hello

Hello world.

From point:

Remember: to run this function from the VLISP Console window, you need to issue the function call with the parentheses because VLISP does not recognize AutoCAD commands.

_$ (c:hello)
Hello world.

If you follow your function definition with a call to the setfunhelp function, you can associate a Help file and topic with a user-defined command. When help is requested during execution of the user-defined command, the topic specified by setfunhelp displays. See the AutoLISP Reference for more information on using setfunhelp.

You cannot usually use an AutoLISP statement to respond to prompts from an AutoLISP-implemented command. However, if your AutoLISP routine makes use of the initget function, you can use arbitrary keyboard input with certain functions. This allows an AutoLISP-implemented command to accept an AutoLISP statement as a response. Also, the values returned by a DIESEL expression can perform some evaluation of the current drawing and return these values to AutoLISP. See Keyword Options for more information on using initget, and refer to the AutoCAD Customization Guide for information on the DIESEL string expression language.


Redefining AutoCAD Commands

Adding Commands
C:XXX Functions
Local Variables in Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling > C:XXX Functions >
Redefining AutoCAD Commands

Using AutoLISP, external commands, and the alias feature, you can define your own AutoCAD commands. You can use the UNDEFINE command to redefine a built-in AutoCAD command with a user-defined command of the same name. To restore the built-in definition of a command, use the REDEFINE command. The UNDEFINE command is in effect for the current editing session only.

You can always activate an undefined command by specifying its true name, which is the command name prefixed by a period. For example, if you undefine QUIT, you can still access the command by entering .quit at the AutoCAD Command prompt. This is also the syntax that should be used within the AutoLISP command function.

Consider the following example. Whenever you use the LINE command, you want AutoCAD to remind you about using the PLINE command. You can define the AutoLISP function C:LINE to substitute for the normalLINEcommand as follows:

_$ (defun C:LINE ( )
(_> (princ "Shouldn't
you be using PLINE?\n")
(_> (command ".LINE")
(princ) )
C:LINE

In this example, the function C:LINE is designed to issue its message and then to execute the normal LINE command (using its true name, .LINE). Before AutoCAD will use your new definition for the LINE command, you must undefine the built-in LINE command. Enter the following to undefine the built-in LINE command:

_$ (command "undefine"
"line")

Now, if you enter line at the AutoCAD Command prompt, AutoCAD uses the C:LINE AutoLISP function:

Command: line

Shouldn't you be using PLINE?

.LINE Specify first point: Specify first point:

The previous code example assumes the CMDECHO system variable is set to 1 (On). If CMDECHO is set to 0 (Off), AutoCAD does not echo prompts during a command function call. The following code uses the CMDECHO system variable to prevent the LINE command prompt from repeating:

_$ (defun C:LINE ( /
cmdsave )
(_> (setq cmdsave (getvar
"cmdecho"))
(_> (setvar "cmdecho"
0)
(_> (princ "Shouldn't
you be using PLINE?\n")
(_> (command ".LINE")
(_> (setvar "cmdecho"
cmdsave)
(_> (princ) )
C:LINE

Now if you enter line at the AutoCAD Command prompt, the following text is displayed:

Shouldn't you be using PLINE?

Specify first point:

You can use this feature in a drawing management system, for example. You can redefine the NEW, OPEN, and QUIT commands to write billing information to a log file before you terminate the editing session.

It is recommended that you protect your menus, scripts, and AutoLISP programs by using the period-prefixed forms of all commands. This ensures that your applications use the built-in command definitions rather than a redefined command.

See the Overview of File Organization topic in the AutoCAD Customization Guide for a description of the steps AutoCAD takes to evaluate command names.


Local Variables in Functions

Redefining AutoCAD Commands
Symbol and Function Handling
Local Variables versus Global Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling >
Local Variables in Functions

AutoLISP provides a method for defining a list of symbols (variables) that are available only to your function. These are known as local variables.

Topics in this section

  • Local Variables versus Global Variables
  • Example Using Local Variables


Local Variables versus Global Variables

Local Variables in Functions
Local Variables in Functions
Example Using Local Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling > Local Variables in Functions >
Local Variables versus Global Variables

The use of local variables ensures that the variables in your functions are unaffected by the surrounding application and that your variables do not remain available after the calling function has completed its task.

Many user-defined functions are used as utility functions within larger applications. User-defined functions also typically contain a number of variables whose values and use are specific to that function.

The danger in using global variables, instead of local variables, is you may inadvertently modify them outside of the function they were declared in and intended for. This can lead to unpredictable behavior, and it can be very difficult to identify the source of this type of problem.

Another advantage of using local variables is that AutoCAD can recycle the memory space used by these variables, whereas global variables keep accumulating within AutoCAD memory space.

There are some legitimate uses for global variables, but these should be kept to a minimum. It is also a good practice to indicate that you intend a variable to be global. A common way of doing this is to add an opening and closing asterisk to the variable name, for example, *default-layer*.


Example Using Local Variables

Local Variables versus Global Variables
Local Variables in Functions
Functions with Arguments
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling > Local Variables in Functions >
Example Using Local Variables

The following example shows the use of local variables in a user-defined function (be certain there is at least one space between the slash and the local variables).

_$ (defun LOCAL ( /
aaa bbb)
(_> (setq aaa "A" bbb
"B")
(_> (princ (strcat "\naaa
has the value " aaa ))
(_> (princ (strcat "\nbbb
has the value " bbb))
(_> (princ) )
LOCAL

Before you test the new function, assign variables aaa and bbb to values other than those used in the LOCAL function.

_$ (setq aaa 1 bbb 2)
2

You can verify that the variables aaa and bbb are actually set to those values.

_$ aaa
1
_$ bbb
2

Now test the LOCAL function.

_$ (local)
aaa has the value A
bbb has the value B

You will notice the function used the values for aaa and bbb that are local to the function. You can verify that the current values for aaa and bbb are still set to their nonlocal values.

_$ aaa
1
_$ bbb
2

In addition to ensuring that variables are local to a particular function, this technique also ensures the memory used for those variables is available for other functions.


Functions with Arguments

Example Using Local Variables
Symbol and Function Handling
Special Forms
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling >
Functions with Arguments

With AutoLISP, you can define functions that accept arguments. Unlike many of the standard AutoLISP functions, user-defined functions cannot have optional arguments. When you call a user-defined function that accepts arguments, you must provide values for all the arguments.

The symbols to use as arguments are defined in the argument list before the local variables. Arguments are treated as a special type of local variable; argument variables are not available outside the function. You cannot define a function with multiple arguments of the same name.

The following code defines a function that accepts two string arguments, combines them with another string, and returns the resulting string.

_$ (defun ARGTEST (
arg1 arg2 / ccc )
(_> (setq ccc "Constant
string")
(_> (strcat ccc ", "
arg1 ", " arg2) )
ARGTEST

The ARGTEST function returns the desired value because AutoLISP always returns the results of the last expression it evaluates. The last line in ARGTEST uses strcat to concatenate the strings, and the resulting value is returned. This is one example where you should not use the princ function to suppress the return value from your program.

This type of function can be used a number of times within an application to combine two variable strings with one constant string in a specific order. Because it returns a value, you can save the value to a variable for use later in the application.

_$ (setq newstr (ARGTEST
"String 1" "String 2") )
"Constant string, String 1, String 2"

The newstr variable is now set to the value of the three strings combined.

Note that the ccc variable was defined locally within the ARGTEST function. Once the function runs to completion, AutoLISP recycles the variable, recapturing the memory allocated to it. To prove this, check from the VLISP Console window to see if there is still a value assigned to ccc.

_$  ccc
nil

Topics in this section

  • Special Forms


Special Forms

Functions with Arguments
Functions with Arguments
Error Handling in AutoLISP
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Symbol and Function Handling > Functions with Arguments >
Special Forms

Certain AutoLISP functions are considered special forms because they evaluate arguments in a different manner than most AutoLISP function calls. A typical function evaluates all arguments passed to it before acting on those arguments. Special forms either do not evaluate all their arguments, or only evaluate some arguments under certain conditions.

The following AutoLISP functions are considered special forms:

  • AND
  • COMMAND
  • COND
  • DEFUN
  • DEFUN-Q
  • FOREACH
  • FUNCTION
  • IF
  • LAMBDA
  • OR
  • PROGN
  • QUOTE
  • REPEAT
  • SETQ
  • TRACE
  • UNTRACE
  • VLAX-FOR
  • WHILE

You can read about each of these functions in the AutoLISP Reference.


Error Handling in AutoLISP

Special Forms
AutoLISP Basics
Using the *error* Function
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics >
Error Handling in AutoLISP

The AutoLISP language provides several functions for error handling. You can use these functions to do the following:

  • Provide information to users when an error occurs during the execution of a program.
  • Restore the AutoCAD environment to a known state.
  • Intercept errors and continue program execution.

The complete list of error-handling functions is in AutoLISP Function Synopsis under the heading Error-Handling Functions Each error-handling function is described in the AutoLISP Reference.

If your program contains more than one error in the same expression, you cannot depend on the order in which AutoLISP detects the errors. For example, the inters function requires several arguments, each of which must be either a 2D or 3D point list. A call to inters like the following:

(inters 'a)

is an error on two counts: too few arguments and invalid argument type. You will receive either of the following error messages:

; *** ERROR: too few arguments
; *** ERROR: bad argument type: 2D/3D point

Your program should be designed to handle either error.

Note also that in AutoCAD, AutoLISP evaluates all arguments before checking the argument types. In previous releases of AutoCAD, AutoLISP evaluated and checked the type of each argument sequentially. To see the difference, look at the following code examples:

(defun foo ()
  (print "Evaluating foo")
  '(1 2))
(defun bar ()
  (print "Evaluating bar")
  'b)
(defun baz ()
  (print "Evaluating baz")
  'c)

Observe how an expression using the inters function is evaluated in AutoCAD:

Command: (inters (foo) (bar) (baz))

"Evaluating foo"

"Evaluating bar"

"Evaluating baz"

; *** ERROR: too few arguments

Each argument was evaluated successfully before AutoLISP passed the results to inters and discovered that too few arguments were specified.

In AutoCAD Release 14 or earlier, the same expression evaluated as follows:

Command: (inters (foo) (bar) (baz))

"Evaluating foo"

"Evaluating bar" error: bad argument type

AutoLISP evaluated (foo), then passed the result to inters. Since the result was a valid 2D point list, AutoLISP proceeds to evaluate (bar), where it determines that the evaluated result is a string, an invalid argument type for inters.

Topics in this section

  • Using the *error* Function
  • Catching Errors and Continuing Program Execution


Using the *error* Function

Error Handling in AutoLISP
Error Handling in AutoLISP
Catching Errors and Continuing Program Execution
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Error Handling in AutoLISP >
Using the *error* Function

Proper use of the *error* function can ensure that AutoCAD returns to a particular state after an error occurs. Through this user-definable function you can assess the error condition and return an appropriate message to the user. If AutoCAD encounters an error during evaluation, it prints a message in the following form:

Error: text

In this message, text describes the error. However, if the *error* function is defined (that is, if it is not nil), AutoLISP executes *error* instead of printing the message. The *error* function receives text as its single argument.

If *error* is not defined or is nil, AutoLISP evaluation stops and displays a traceback of the calling function and its callers. It is beneficial to leave this error handler in effect while you debug your program.

A code for the last error is saved in the AutoCAD system variable ERRNO, where you can retrieve it by using the getvar function. See Error Handling in AutoLISP for a list of error codes and their meaning.

Before defining your own *error* function, save the current contents of *error* so that the previous error handler can be restored upon exit. When an error condition exists, AutoCAD calls the currently defined *error* function and passes it one argument, which is a text string describing the nature of the error. Your *error* function should be designed to exit quietly after an ESC (cancel) or an exit function call. The standard way to accomplish this is to include the following statements in your error-handling routine.

(if
  (or
    (= msg "Function cancelled")
    (= msg "quit / exit abort")
  )
  (princ)
  (princ (strcat "\nError: " msg))
)

This code examines the error message passed to it and ensures that the user is informed of the nature of the error. If the user cancels the routine while it is running, nothing is returned from this code. Likewise, if an error condition is programmed into your code and the exit function is called, nothing is returned. It is presumed you have already explained the nature of the error by using print statements. Remember to include a terminating call to princ if you don't want a return value printed at the end of an error routine.

The main caveat about error-handling routines is they are normal AutoLISP functions that can be canceled by the user. Keep them as short and as fast as possible. This will increase the likelihood that an entire routine will execute if called.

You can also warn the user about error conditions by displaying an alert box, which is a small dialog box containing a message supplied by your program. To display an alert box, call the alert function.

The following call to alert displays an alert box:

(alert "File not found")


Catching Errors and Continuing Program Execution

Using the *error* Function
Error Handling in AutoLISP
Using AutoLISP to Communicate with AutoCAD
AutoLISP Developer's Guide > Using the AutoLISP Language > AutoLISP Basics > Error Handling in AutoLISP >
Catching Errors and Continuing Program Execution

Your program can intercept and attempt to process errors instead of allowing control to pass to *error*. The vl-catch-all-apply function is designed to invoke any function, return a value from the function, and trap any error that may occur. The function requires two arguments: a symbol identifying a function or lambda expression, and a list of arguments to be passed to the called function. The following example uses vl-catch-all-apply to divide two numbers:

_$ (setq catchit (vl-catch-all-apply
'/ '(50 5)))
10

The result from this example is the same as if you had used apply to perform the division.

The value of vl-catch-all-apply is in catching errors and allowing your program to continue execution.

To catch errors with vl-catch-all-apply

  1. The following code defines a function named catch-me-if-you-can. Copy the code into a VLISP text editor window:
    (defun catch-me-if-you-can (dividend divisor / errobj)
      (setq errobj (vl-catch-all-apply '/ (list dividend divisor)))
      (if (vl-catch-all-error-p errobj)
        (progn
          (print (strcat "An error occurred: "
                         (vl-catch-all-error-message errobj)
                 )
          )
          (prompt "Do you want to continue? (Y/N) -> ")
          (setq ans (getstring))
          (if (equal (strcase ans) "Y")
            (print "Okay, I'll keep going")
          )
        )
        (print errobj)
      )
      (princ)
    )

    This function accepts two number arguments and uses vl-catch-all-apply to divide the first number by the second number. The vl-catch-all-error-p function determines whether the return value from vl-catch-all-apply is an error object. If the return value is an error object, catch-me-if-you-can invokes vl-catch-all-error-message to obtain the message from the error object.

  2. Load the function.
  3. Invoke the function with the following command:
    (catch-me-if-you-can
50 2)

    The function should return 25.

  4. Intentionally cause an error condition by invoking the function with the following command:
    (catch-me-if-you-can
50 0)

    The function should issue the following prompt in the AutoCAD Command window:

    "An error occurred: divide by zero" Do you want to continue? (Y/N) ->

    If you enter y, catch-me-if-you-can indicates that it will continue processing.

    Try modifying this example by changing vl-catch-all-apply to apply. Load and run the example with a divide by zero again. When apply results in an error, execution immediately halts and *error* is called, resulting in an error message.

    The vl-catch-* functions are especially important when you use ActiveX with AutoLISP. Many of the AutoCAD ActiveX automation methods are designed to be used in the “programming by exception” style. This means they either return useful values if they succeed, or raise an exception if they fail (instead of returning an error value). If your program uses ActiveX methods, you must prepare it to catch exceptions, otherwise the program halts, leaving the user at a Command prompt. See Handling Errors Returned by ActiveX Methods for an example using vl-catch-all-apply with ActiveX.


Using AutoLISP to Communicate with AutoCAD

Catching Errors and Continuing Program Execution
Using the AutoLISP Language
Accessing Commands and Services
AutoLISP Developer's Guide > Using the AutoLISP Language >
Using AutoLISP to Communicate with AutoCAD

Query and command functions provide direct access to AutoCAD commands and drawing services.

AutoLISP® provides various functions for examining the contents of the currently loaded drawing. This chapter introduces these functions and describes how to use them in conjunction with other functions.

Topics in this section

  • Accessing Commands and Services
  • Display Control
  • Getting User Input
  • Geometric Utilities
  • Conversions
  • File Handling
  • Device Access and Control


Accessing Commands and Services

Using AutoLISP to Communicate with AutoCAD
Using AutoLISP to Communicate with AutoCAD
Command Submission
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
Accessing Commands and Services

The query and command functions described in this section provide direct access to AutoCAD® commands and drawing services. Their behavior depends on the current state of the AutoCAD system and environment variables, and on the drawing that is currently loaded. See ##xref here - Query and Command Functions (app A Utility functions) in AutoLISP Function Synopsis for a complete list of query and command functions.

NoteThe AutoLISP examples in this chapter show code entered at the AutoCAD Command prompt, not the Visual LISP Console window.

Topics in this section

  • Command Submission
  • System and Environment Variables
  • Configuration Control


Command Submission

Accessing Commands and Services
Accessing Commands and Services
Foreign Language Support
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services >
Command Submission

The command function sends an AutoCAD command directly to the AutoCAD Command prompt. The command function has a variable-length argument list. These arguments must correspond to the types and values expected by that command's prompt sequence; these may be strings, real values, integers, points, entity names, or selection set names. Data such as angles, distances, and points can be passed either as strings or as the values themselves (as integer or real values, or as point lists). An empty string ("") is equivalent to pressing the SPACEBAR or ENTER on the keyboard.

There are some restrictions on the commands that you can use with the command function. See the AutoLISP Reference definition of this function for information on these restrictions.

The following code fragment shows representative calls to command.

(command "circle" "0,0" "3,3")
(command "thickness" 1)
(setq p1  '(1.0 1.0 3.0))
(setq rad 4.5)
(command "circle" p1 rad)

If AutoCAD is at the Command prompt when these functions are called, AutoCAD performs the following actions:

  1. The first call to command passes points to the CIRCLE command as strings (draws a circle centered at 0.0,0.0 and passes through 3.0,3.0).
  2. The second call passes an integer to the THICKNESS system variable (changes the current thickness to 1.0).
  3. The last call uses a 3D point and a real (floating-point) value, both of which are stored as variables and passed by reference to the CIRCLE command. This draws an extruded circle centered at (1.0,1.0,3.0) with a radius of 4.5.

Topics in this section

  • Foreign Language Support
  • Pausing for User Input
  • Passing Pick Points to AutoCAD Commands
  • Undoing Commands Issued with the command Function


Foreign Language Support

Command Submission
Command Submission
Pausing for User Input
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services > Command Submission >
Foreign Language Support

If you develop AutoLISP programs that can be used with a foreign language version of AutoCAD, the standard AutoCAD commands and keywords are automatically translated if you precede each command or keyword with an underscore (_).

(command "_line" pt1 pt2 pt3 "_c")

If you are using the dot prefix (to avoid using redefined commands), you can place the dot and underscore in either order. Both "._line" and "_.line" are valid.


Pausing for User Input

Foreign Language Support
Command Submission
Passing Pick Points to AutoCAD Commands
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services > Command Submission >
Pausing for User Input

If an AutoCAD command is in progress and the predefined symbol PAUSE is encountered as an argument to command, the command is suspended to allow direct user input (usually point selection or dragging). This is similar to the backslash pause mechanism provided for menus.

The PAUSE symbol is defined as a string consisting of a single backslash. When you use a backslash (\) in a string, you must precede it by another backslash (\\).

Menu input is not suspended by an AutoLISP pause. If a menu item is active when the command function pauses for input, that input request can be satisfied by the menu. If you want the menu item to be suspended as well, you must provide a backslash in the menu item. When valid input is found, both the command function and the menu item resume.

NoteYou can use a backslash instead of the PAUSE symbol. However, it is recommended that you always use the PAUSE symbol rather than an explicit backslash. Also, if the command function is invoked from a menu item, the backslash suspends the reading of the menu item, which results in partial evaluation of the AutoLISP expression.

If you issue a transparent command while a command function is suspended, the command function remains suspended. Therefore, users can 'ZOOM and 'PAN while at a command pause. The pause remains in effect until AutoCAD gets valid input, and no transparent command is in progress. For example, the following code begins the CIRCLE command, sets the center point at (5,5), and then pauses to let the user drag the circle's radius. When the user specifies the desired point (or types in the desired radius), the function resumes, drawing a line from (5,5) to (7,5), as follows:

(command "circle" "5,5" pause "line" "5,5" "7,5" "")

If PAUSE is encountered when a command is expecting input of a text string or an attribute value, AutoCAD pauses for input only if the TEXTEVAL system variable is nonzero. Otherwise, AutoCAD does not pause for user input but uses the value of the PAUSE symbol (a single backslash) text.

When the command function pauses for user input, the function is considered active, so the user cannot enter another AutoLISP expression to be evaluated.

The following is an example of using the PAUSE symbol (the layer NEW_LAY and the block MY_BLOCK must exist in the drawing prior to testing this code):

(setq blk "MY_BLOCK")
(setq old_lay (getvar "clayer"))
(command "layer" "set" "NEW_LAY" "")
(command "insert" blk pause "" "" pause)
(command "layer" "set" old_lay "")

The preceding code fragment sets the current layer to NEW_LAY, pauses for user selection of an insertion point for the block MY_BLOCK (which is inserted with X and Y scale factors of 1), and pauses again for user selection of a rotation angle. The current layer is then reset to the original layer.

If the command function specifies a PAUSE to the SELECT command and a PICKFIRST set is active, the SELECT command obtains the PICKFIRST set without pausing for the user.

WarningThe Radius and Diameter subcommands of the Dim prompt issue additional prompts in some situations. This can cause a failure of AutoLISP programs written prior to Release 11 that use these commands.


Passing Pick Points to AutoCAD Commands

Pausing for User Input
Command Submission
Undoing Commands Issued with the command Function
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services > Command Submission >
Passing Pick Points to AutoCAD Commands

Some AutoCAD commands (such as TRIM, EXTEND, and FILLET) require the user to specify a pick point as well as the object itself. To pass such pairs of object and point data by means of the command function without the use of a PAUSE, you must first store them as variables. Points can be passed as strings within the command function or can be defined outside the function and passed as variables, as shown in the following example. This code fragment shows one method of passing an entity name and a pick point to the command function.

(command "circle" "5,5" "2")        Draws
circle
(command "line" "3,5" "7,5" "")     Draws
line
(setq el  (entlast))                Gets
last entity name
(setq pt  '(5 7))                   Sets point pt
(command "trim" el "" pt "")        Performs
trim

If AutoCAD is at the Command prompt when these functions are called, AutoCAD performs the following actions:

  1. Draws a circle centered at (5,5) with a radius of 2.
  2. Draws a line from (3,5) to (7,5).
  3. Creates a variable el that is the name of the last object added to the database. (See Using AutoLISP to Manipulate AutoCAD Objects for more discussion of objects and object-handling functions.)
  4. Creates a pt variable that is a point on the circle. (This point selects the portion of the circle to be trimmed.)
  5. Performs the TRIM command by selecting the el object and by selecting the point specified by pt.


Undoing Commands Issued with the command Function

Passing Pick Points to AutoCAD Commands
Command Submission
System and Environment Variables
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services > Command Submission >
Undoing Commands Issued with the command Function

An UNDO group is explicitly created around each command used with the command function. If a user enters U (or UNDO) after running an AutoLISP routine, only the last command will be undone. Additional entries of UNDO will step backward through the commands used in that routine. If you want a group of commands to be considered a group (or the entire routine), use the UNDO Begin and UNDO End options.


System and Environment Variables

Undoing Commands Issued with the command Function
Accessing Commands and Services
Configuration Control
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services >
System and Environment Variables

With the getvar and setvar functions, AutoLISP applications can inspect and change the value of AutoCAD system variables. These functions use a string to specify the variable name. The setvar function specifies a value of the type that the system variable expects. AutoCAD system variables come in various types: integers, real values, strings, 2D points, and 3D points. Values supplied as arguments to setvar must be of the expected type. If an invalid type is supplied, an AutoLISP error is generated.

The following code fragment ensures that subsequent FILLET commands use a radius of at least 1:

(if (< (getvar "filletrad") 1)
  (setvar "filletrad" 1)
)

See the Command Reference for a list of AutoCAD system variables and their descriptions.

An additional function, getenv, provides AutoLISP routines with access to the currently defined operating system environment variables.


Configuration Control

System and Environment Variables
Accessing Commands and Services
Display Control
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Accessing Commands and Services >
Configuration Control

AutoCAD uses the acadxx.cfg file to store configuration information (the xx in the file name refers to the AutoCAD release number). The AppData section of this file is provided for users and developers to store configuration information pertaining to their applications. The getcfg and setcfg functions allow AutoLISP applications to inspect and change the value of parameters in the AppData section.


Display Control

Configuration Control
Using AutoLISP to Communicate with AutoCAD
Controlling Menus
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
Display Control

AutoLISP includes functions for controlling the AutoCAD display in both text and graphics windows. Some functions prompt for, or depend on, input from the AutoCAD user.

The prompt, princ, prin1, and print functions are the primary text output functions. These functions were described in the AutoLISP Basics chapter, under the heading, Basic Output Functions

See Display Control Functions in AutoLISP Function Synopsis for a complete list of display control functions.

Topics in this section

  • Controlling Menus
  • Control of Graphics and Text Windows
  • Control of Low-Level Graphics


Controlling Menus

Display Control
Display Control
Control of Graphics and Text Windows
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Display Control >
Controlling Menus

The menucmd function controls the display of the graphics window menus. It displays, modifies, or queries one of the submenus of the current menu, and accepts a string argument that specifies the submenu and the action to perform on that submenu.

The menucmd function takes a string argument that consists of two fields, separated by an equal sign, in the following form:

"menu_area=action"

This syntax can load a submenu into a specified menu area, or perform an action on a menu item or a currently loaded menu area. The menu_area field specifies which part of the menu is to receive the action. This field can specify a menu area, such as P0 (for the shortcut menu) or S (for the screen menu), or a specific menu item. The action field specifies the action to perform on the menu area or menu item, or a submenu to load into the menu area. The menu areas that can receive an action are the same as those used in menu file submenu references.

Every menu area has a currently loaded submenu. By default, the first submenu following a menu section label is loaded into that menu area.

If menu_area specifies a pull-down menu or image tile menu, action can be an asterisk (*). This causes the menu to display (pull-down menus and image tile menus are not automatically displayed when they are called). In Windows, only the P0 (cursor) menu and image tile menus are displayed with the asterisk.

NoteDo not include the dollar sign that introduces the similar instructions in a menu file in the string argument. Also, do not include the asterisks that precede submenu labels in the menu file in the action field of the string argument.

The following menucmd function call causes the **OSNAP screen submenu defined in the current menu file to be displayed (assuming the screen menu is currently enabled).

(menucmd "S=OSNAP")

In Windows, you can reference the menu group. This can be useful if there are multiple menus loaded that contain the same submenu name. The following code displays the **OSNAP screen submenu in the ACAD menu group.

(menucmd "S=ACAD.OSNAP")

The menucmd function can load submenus into the BUTTONS and AUX menu areas. You might want your digitizer buttons to function differently depending on whether Tablet mode is on or off. You can have two submenus defined in the ***BUTTONS1 section, **DIG-BUTTONS and **TAB-BUTTONS, and switch between them with the following code.

(menucmd "B1=DIG-BUTTONS")  Enables the DIG-BUTTONS submenu
(menucmd "B1=TAB-BUTTONS")  Enables the TAB-BUTTONS submenu

The following code loads the ***POP0 menu into the P0 (cursor) menu area and displays it.

(menucmd "P0=POP0")         Loads
the ***POP0 menu into the P0 menu area
(menucmd "P0=*") 						Displays
it

If you are sure the correct menu is loaded into a particular menu area, you do not need to load it specifically each time you want to display it.

The following call displays the pull-down menu currently loaded in the P1 (first pull-down menu) location.

(menucmd "P1=*")

Using "P1=*" without previously loading the menu can result in unexpected behavior. Although you can load virtually any menu at a pull-down or shortcut menu location, it is best to use only menus specifically designed for that menu area. For example, if you have a submenu called **MORESTUFF, you can load it at the P1 location with the following code:

(menucmd "P1=MORESTUFF")    Loads the **MORESTUFF menu in the
P1 menu location
(menucmd "P1=*")            Displays
it

This menu remains in this location until you replace it by loading another menu, as in the following:

(menucmd "P1=POP1")

If your menu uses the disabling (graying-out) and marking features, you can retrieve and change the state of a menu label with the menucmd function. The following call retrieves the current state of the fourth label in the pull-down menu P2.

(menucmd "P2.4=#?")         If
disabled returns   "P2.4=~"

These function calls enable and disable that same label:

(menucmd "P2.4=")           Enables
the label
(menucmd "P2.4=~")          Disables
the label

You can also place and remove marks to the left of menu labels.

The previously described method of menu item handling works relatively well with a single static menu. However, it becomes unreliable when menu item locations change when you load multiple partial menu files. You can make use of the menu-group and name-tag features to keep track of menu items. Instead of specifying a menu item by its location in the menu file, you specify the menu group and name tag associated with the menu item.

When you use the menu group to enable, disable, and mark menu labels, you must precede the group name with a G, as shown in the following examples.

(menucmd "Gacad.ID_New=~")  Disables the
label
(menucmd "Gacad.ID_New=")   Enables the
label

Not only can an AutoLISP function enable and disable menu labels, it can also modify the text displayed in the label by placing a DIESEL string expression in the label. Because DIESEL accepts only strings as input, you can pass information to the DIESEL expression through a USERS1-5 system variable that has been set to a value returned by your function.

You can also use the menucmd function to evaluate DIESEL string expressions within an AutoLISP function. The following routine returns the current time:

(defun C:CTIME ( / ctim)
  (setq ctim
    (menucmd "M=$(edtime,$(getvar,date),H:MMam/pm)"))
  (princ (strcat "\nThe current time is " ctim ))
  (princ)
)

For information on the use of DIESEL expressions with AutoLISP and a catalog of DIESEL functions, see the Customization Guide. Refer also to the Customization Guide for further information on menus.


Control of Graphics and Text Windows

Controlling Menus
Display Control
Control of Low-Level Graphics
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Display Control >
Control of Graphics and Text Windows

You can control the display of the graphics and text windows from an AutoLISP application. On single-screen AutoCAD installations, a call to graphscr displays the graphics window, and a call to textscr displays the text window. Using these functions is equivalent to toggling the Flip Screen function key. The function textpage is equivalent to textscr.

The redraw function is similar to the AutoCAD REDRAW command but provides more control over what is displayed. It not only redraws the entire graphics area but can also specify a single object to be redrawn or undrawn (that is, blanked out). If the object is a complex object such as an old-style polyline or a block, redraw can draw (or undraw) either the entire object or its header. The redraw function can also highlight and unhighlight specified objects.


Control of Low-Level Graphics

Control of Graphics and Text Windows
Display Control
Getting User Input
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Display Control >
Control of Low-Level Graphics

AutoLISP provides functions that control the low-level graphics and allow direct access to the AutoCAD graphics screen and input devices.

The grtext function displays text directly in the status or menu areas, with or without highlighting. The grdraw function draws a vector in the current viewport with control over color and highlighting. The grvecs function draws multiple vectors.

NoteBecause these functions depend on code in AutoCAD, their operation can be expected to change from release to release. There is no guarantee that applications calling these functions will be upward compatible. Also, they depend on current hardware configurations. In particular, applications that call grtext are not likely to work the same on all configurations unless the developer is very careful to use them as described (see the Customization Guide) and to avoid hardware-specific features. Finally, because they are low-level functions, they do almost no error reporting and can alter the graphics screen display unexpectedly (see the following example for a way to fix this).

The following sequence restores the default graphics window display caused by incorrect calls to grtext, grdraw, or grvecs:

(grtext)       Restores
standard text
(redraw)


Getting User Input

Control of Low-Level Graphics
Using AutoLISP to Communicate with AutoCAD
The getxxx Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
Getting User Input

Several functions enable an AutoLISP application to prompt the user for input of data. See User Input Functions in AutoLISP Function Synopsis for a complete list of user input functions.

Topics in this section

  • The getxxx Functions
  • Control of User-Input Function Conditions


The getxxx Functions

Getting User Input
Getting User Input
Control of User-Input Function Conditions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Getting User Input >
The getxxx Functions

Each user-input getxxx function pauses for data entry of the indicated type and returns the value entered. The application specifies an optional prompt to display before the function pauses. The following table lists the getxxx functions and the type of user input requested.

Allowable input to the getxxx user-input functions
Function name | Type of user input
getint | An integer value on the command line
getreal | A real or integer value on the command line
getstring | A string on the command line
getpoint | A point value on the command line or selected from the screen
getcorner | A point value (the opposite corner of a box) on the command line or selected from the screen
getdist | A real or integer value (of distance) on the command line or determined by selecting points on the screen
getangle | An angle value (in the current angle format) on the command line or based on selected points on the screen
getorient | An angle value (in the current angle format) on the command line or based on selected points on the screen
getkword | A predefined keyword or its abbreviation on the command line
NoteAlthough the getvar, getcfg, and getenv functions begin with the letters g, e, and t, they are not user-input functions. They are discussed in Accessing Commands and Services.

The functions getint, getreal, and getstring pause for user input on the AutoCAD command line. They return a value only of the same type as that requested.

The getpoint, getcorner, and getdist functions pause for user input on the command line or from points selected on the graphics screen. The getpoint and getcorner functions return 3D point values, and getdist returns a real value.

Both getangle and getorient pause for input of an angle value on the command line or as defined by points selected on the graphics screen. For the getorient function, the 0 angle is always to the right: “East” or “3 o'clock.” For getangle, the 0 angle is the value of ANGBASE, which can be set to any angle. Both getangle and getorient return an angle value (a real) in radians measured counterclockwise from a base (0 angle), for getangle equal to ANGBASE, and for getorient to the right.

For example, ANGBASE is set to 90 degrees (north), and ANGDIR is set to 1 (clockwise direction for increasing angles). The following table shows what getangle and getorient return (in radians) for representative input values (in degrees).

Possible return values from getangle and getorient
Input (degrees) | getangle | getorient
0 | 0.0 | 1.5708
-90 | 1.5708 | 3.14159
180 | 3.14159 | 4.71239
90 | 4.71239 | 0.0

The getangle function honors the settings of ANGDIR and ANGBASE when accepting input. You can use getangle to obtain a rotation amount for a block insertion, because input of 0 degrees always returns 0 radians. The getorient function honors only ANGDIR. You use getorient to obtain angles such as the baseline angle for a text object. For example, given the preceding settings of ANGBASE and ANGDIR, for a line of text created at an angle of 0, getorient returns an angle value of 90.

The user-input functions take advantage of the error-checking capability of AutoCAD. Trivial errors are trapped by AutoCAD and are not returned by the user-input function. A prior call to initget provides additional filtering capabilities, lessening the need for error-checking.

The getkword function pauses for the input of a keyword or its abbreviation. Keywords must be defined with the initget function before the call to getkword. All user-input functions (except getstring) can accept keyword values in addition to the values they normally return, provided that initget has been called to define the keywords.

All user-input functions allow for an optional prompt argument. It is recommended you use this argument rather than a prior call to the prompt or princ functions. If a prompt argument is supplied with the call to the user-input function, that prompt is reissued in the case of invalid user input. If no prompt argument is supplied and the user enters incorrect information, the following message appears at the AutoCAD prompt line:

Try again:

This can be confusing, because the original prompt may have scrolled out of the Command prompt area.

The AutoCAD user cannot typically respond to a user-input function by entering an AutoLISP expression. If your AutoLISP routine makes use of the initget function, arbitrary keyboard input is permitted to certain functions that can allow an AutoLISP statement as response to a command implemented in AutoLISP. This is discussed in Arbitrary Keyboard Input.


Control of User-Input Function Conditions

The getxxx Functions
Getting User Input
Input Options for User-Input Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Getting User Input >
Control of User-Input Function Conditions

The initget function provides a level of control over the next user-input function call. The initget function establishes various options for use by the next entsel, nentsel, nentselp, or getxxx function (except getstring, getvar, and getenv). This function accepts two arguments, bits and string, both of which are optional. The bits argument specifies one or more control bits that enable or disable certain input values to the next user-input function call. The string argument can specify keywords that the next user-input function call will recognize.

The control bits and keywords established by initget apply only to the next user-input function call. They are discarded after that call. The application doesn't have to call initget a second time to clear special conditions.

Topics in this section

  • Input Options for User-Input Functions
  • Keyword Options
  • Arbitrary Keyboard Input
  • Input Validation


Input Options for User-Input Functions

Control of User-Input Function Conditions
Control of User-Input Function Conditions
Keyword Options
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Getting User Input > Control of User-Input Function Conditions >
Input Options for User-Input Functions

The value of the bits argument restricts the types of user input to the next user-input function call. This reduces error-checking. These are some of the available bit values: 1 disallows null input, 2 disallows input of 0 (zero), and 4 disallows negative input. If these values are used with a following call to the getint function, the user is forced to enter an integer value greater than 0.

To set more than one condition at a time, add the values together (in any combination) to create a bits value between 0 and 255. If bits is not included or is set to 0, none of the control conditions applies to the next user-input function call. (For a complete listing of initget bit settings, see initget in the AutoLISP Reference.)

(initget (+ 1 2 4))
(getint "\nHow old are you? ")

This sequence requests the user's age. AutoCAD displays an error message and repeats the prompt if the user attempts to enter a negative or zero value, or if the user only presses ENTER, or enters a string (the getint function rejects attempts to enter a value that is not an integer).


Keyword Options

Input Options for User-Input Functions
Control of User-Input Function Conditions
Arbitrary Keyboard Input
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Getting User Input > Control of User-Input Function Conditions >
Keyword Options

The optional string argument specifies a list of keywords recognized by the next user-input function call.

The initget function allows keyword abbreviations to be recognized in addition to the full keywords. The user-input function returns a predefined keyword if the input from the user matches the spelling of a keyword (not case sensitive), or if the user enters the abbreviation of a keyword. There are two methods for abbreviating keywords; both are discussed in the initget topic in the AutoLISP Reference.

The following user-defined function shows a call to getreal, preceded by a call to initget, that specifies two keywords. The application checks for these keywords and sets the input value accordingly.

(defun C:GETNUM (/ num)
  (initget 1 "Pi Two-pi")
  (setq num (getreal "Pi/Two-pi/<number>: "))
  (cond
    ((eq num "Pi") pi)
    ((eq num "Two-pi") (* 2.0 pi))
    (T num)
  )
)

This initget call inhibits null input (bits = 1) and establishes a list of two keywords, "Pi" and "Two-pi". The getreal function is then used to obtain a real number, issuing the following prompt:

Pi/Two-pi/<number>:

The result is placed in local symbol num. If the user enters a number, that number is returned by C:GETNUM. However, if the user enters the keyword Pi (or simply P), getreal returns the keyword Pi. The cond function detects this and returns the value of p in this case. The Two-pi keyword is handled similarly.

NoteYou can also use initget to enable entsel, nentsel, and nentselp to accept keyword input. For more information on these functions, see Object Handling and the entsel, nentsel and nentselp function definitions in the AutoLISP Reference.


Arbitrary Keyboard Input

Keyword Options
Control of User-Input Function Conditions
Input Validation
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Getting User Input > Control of User-Input Function Conditions >
Arbitrary Keyboard Input

The initget function also allows arbitrary keyboard input to most getxxx functions. This input is passed back to the application as a string. An application using this facility can be written to permit the user to call an AutoLISP function at a getxxx function prompt.

These functions show a method for allowing AutoLISP response to a getxxx function call:

(defun C:ARBENTRY ( / pt1)
  (initget 128)                     ; Sets arbitrary entry bit
  (setq pt1 (getpoint "\nPoint: ")) ; Gets value from user.
  (if (= 'STR (type pt1))           ; If it's a string, convert it
    (setq pt1 (eval (read pt1)))    ; to a symbol, try evaluating
                                    ; it as a function; otherwise,
    pt1                             ; just return the value.
  )
)
(defun REF ( )
  (setvar "LASTPOINT" (getpoint "\nReference point: "))
  (getpoint "\nNext point: " (getvar "LASTPOINT"))
)

If both the C:ARBENTRY and REF functions are loaded into the drawing, the following command sequence is acceptable.

Command: arbentry

Point: (ref)

Reference point: Select a point

Next point: @1,1,0


Input Validation

Arbitrary Keyboard Input
Control of User-Input Function Conditions
Geometric Utilities
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Getting User Input > Control of User-Input Function Conditions >
Input Validation

You should protect your code from unintentional user errors. The AutoLISP user input getxxx functions do much of this for you. However, it's dangerous to forget to check for adherence to other program requirements that the getxxx functions do not check for. If you neglect to check input validity, the program's integrity can be seriously affected.


Geometric Utilities

Input Validation
Using AutoLISP to Communicate with AutoCAD
Object Snap
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
Geometric Utilities

A group of functions allows applications to obtain pure geometric information and geometric data from the drawing. See Geometric Functions in AutoLISP Function Synopsis for a complete list of geometric utility functions.

The angle function finds the angle in radians between a line and the X axis (of the current UCS), distance finds the distance between two points, and polar finds a point by means of polar coordinates (relative to an initial point). The inters function finds the intersection of two lines. The osnap and textbox functions are described separately.

The following code fragment shows calls to the geometric utility functions:

(setq pt1 '(3.0 6.0 0.0))
(setq pt2 '(5.0 2.0 0.0))
(setq base '(1.0 7.0 0.0))
(setq rads  (angle pt1 pt2))    ; Angle in XY plane of current UCS
                                ; (value is returned in radians)
(setq len  (distance pt1 pt2))  ; Distance in 3D space
(setq endpt  (polar base rads len))

The call to polar sets endpt to a point that is the same distance from (1,7) as pt1 is from pt2, and at the same angle from the X axis as the angle between pt1 and pt2.

Topics in this section

  • Object Snap
  • Text Extents


Object Snap

Geometric Utilities
Geometric Utilities
Text Extents
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Geometric Utilities >
Object Snap

The osnap function can find a point by using one of the AutoCAD Object Snap modes. The Snap modes are specified in a string argument.

The following call to osnap looks for the midpoint of an object near pt1:

(setq pt2 (osnap pt1 "midp"))

The following call looks for the midpoint, the endpoint, or the center of an object nearest pt1:

(setq pt2 (osnap pt1 "midp,endp,center"))

In both examples, pt2 is set to the snap point if one is found that fulfills the osnap requirements. If more than one snap point fulfills the requirements, the point is selected based on the setting of the SORTENTS system variable. Otherwise, pt2 is set to nil.

NoteThe APERTURE system variable determines the allowable proximity of a selected point to an object when you use Object Snap.


Text Extents

Object Snap
Geometric Utilities
Conversions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Geometric Utilities >
Text Extents

The textbox function returns the diagonal coordinates of a box that encloses a text object. It takes an entity definition list of the type returned by entget (an association list of group codes and values) as its single argument. This list can contain a complete association list description of the text object or just a list describing the text string.

The points returned by textbox describe the bounding box (an imaginary box that encloses the text object) of the text object, as if its insertion point were located at (0,0,0) and its rotation angle were 0. The first list returned is the point (0.0 0.0 0.0), unless the text object is oblique or vertical or it contains letters with descenders (such as g and p). The value of the first point list specifies the offset distance from the text insertion point to the lower-left corner of the smallest rectangle enclosing the text. The second point list specifies the upper-right corner of that box. The returned point lists always describe the bottom-left and upper-right corners of this bounding box, regardless of the orientation of the text being measured.

The following example shows the minimum allowable entity definition list that textbox accepts. Because no additional information is provided, textbox uses the current defaults for text style and height.

Command: (textbox '((1 . "Hello world")) )

((0.0 0.0 0.0) (2.80952 1.0 0.0))

The actual values returned by textbox will vary depending on the current text style.

The following example demonstrates one method of providing the textbox function with an entity definition list.

Command: dtext

Justify/Style/<Start point>: 1,1

Height <1.0000>: ENTER

Rotation angle <0>: ENTER

Text: test

Text: ENTER

Command: (setq e (entget (entlast)))

((-1 . <Entity name: 1ba3568>) (0 . "TEXT") (330 . <Entity name: 1ba34f8>) (5 .

"2D") (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "0") (100 .

"AcDbText") (10 1.0 1.0 0.0) (40 . 1.0) (1 . "test") (50 . 0.0) (41 . 1.0) (51

. 0.0) (7 . "Standard") (71 . 0) (72 . 0) (11 0.0 0.0 0.0) (210 0.0 0.0 1.0)

(100 . "AcDbText") (73 . 0))

Command: (textbox e)

((0.0 0.0 0.0) (0.8 0.2 0.0))

The following figure shows the results of applying textbox to a text object with a height of 1.0. The figure also shows the baseline and insertion point of the text.

If the text is vertical or rotated, pt1 is still the bottom-left corner and pt2 is the upper-right corner; the bottom-left point may have negative offsets if necessary.

The following figure shows the point values (pt1 and pt2) that textbox returns for samples of vertical and aligned text. In both samples, the height of the letters is 1.0. (For the aligned text, the height is adjusted to fit the alignment points.)

When using vertical text styles, the points are still returned in left-to-right, bottom-to-top order as they are for horizontal styles, so that the first point list will contain negative offsets from the text insertion point.

Regardless of the text orientation or style, the points returned by textbox are such that the text insertion point (group code 10) directly translates to the origin point of the object coordinate system (OCS) for the associated text object. This point can be referenced when translating the coordinates returned from textbox into points that define the actual extent of the text. The two sample routines that follow use textbox to place a box around selected text regardless of its orientation.

The first routine uses the textbox function to draw a box around a selected text object:

(defun C:TBOX ( / textent tb ll ur ul lr)
  (setq textent (car (entsel "\nSelect text: ")))
  (command "ucs" "Object" textent)
  (setq tb (textbox (list  (cons -1 textent)))
        ll (car tb)
        ur  (cadr tb)
        ul  (list (car ll) (cadr ur))
        lr (list (car ur) (cadr ll))
  )
  (command "pline" ll lr ur ul "Close")
  (command "ucs" "p")
  (princ)
)

The second routine, which follows, accomplishes the same task as the first routine by performing the geometric calculations with the sin and cos AutoLISP functions. The result is correct only if the current UCS is parallel to the plane of the text object.

(defun C:TBOX2 ( / textent ang sinrot cosrot
                   t1 t2 p0 p1 p2 p3 p4)
  (setq textent (entget (car (entsel "\nSelect text: "))))
  (setq p0 (cdr (assoc 10 textent))
        ang (cdr (assoc 50 textent))
        sinrot (sin ang)
        cosrot (cos ang)
        t1 (car (textbox textent))
        t2 (cadr (textbox textent))
        p1 (list
          (+ (car p0)
            (- (* (car t1) cosrot)(* (cadr t1) sinrot))
          )
          (+ (cadr p0)
            (+ (* (car t1) sinrot)(* (cadr t1) cosrot))
          )
      )
      p2 (list
        (+ (car p0)
          (- (* (car t2) cosrot)(* (cadr t1) sinrot))
        )
        (+ (cadr p0)
          (+ (* (car t2) sinrot)(* (cadr t1) cosrot))
        )
      )
      p3 (list
        (+ (car p0)
          (- (* (car t2) cosrot)(* (cadr t2) sinrot))
        )
        (+ (cadr p0)
          (+ (* (car t2) sinrot)(* (cadr t2) cosrot))
        )
      )
      p4 (list
        (+ (car p0)
          (- (* (car t1) cosrot)(* (cadr t2) sinrot))
        )
        (+ (cadr p0)
          (+ (* (car t1) sinrot)(* (cadr t2) cosrot))
        )
      )
  )
  (command "pline" p1 p2 p3 p4 "c")
  (princ)
)


Conversions

Text Extents
Using AutoLISP to Communicate with AutoCAD
String Conversions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
Conversions

The functions described in this section are utilities for converting data types and units. See in AutoLISP Function Synopsis for a complete list of conversion functions.

Topics in this section

  • String Conversions
  • Angular Conversion
  • ASCII Code Conversion
  • Unit Conversion
  • Coordinate System Transformations


String Conversions

Conversions
Conversions
Angular Conversion
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions >
String Conversions

The functions rtos (real to string) and angtos (angle to string) convert numeric values used in AutoCAD to string values that can be used in output or as textual data. The rtos function converts a real value, and angtos converts an angle. The format of the result string is controlled by the value of AutoCAD system variables: the units and precision are specified by LUNITS and LUPREC for real (linear) values and by AUNITS and AUPREC for angular values. For both functions, the dimensioning variable DIMZIN controls how leading and trailing zeros are written to the result string.

The following code fragments show calls to rtos and the values returned (assuming the DIMZIN system variable equals 0). Precision (the third argument to rtos) is set to 4 places in the first call and 2 places in the others.

(setq x 17.5)
(setq str "\nValue formatted as ")
(setq fmtval  (rtos x 1 4))    ; Mode 1 = scientific
(princ (strcat str fmtval))    ; displays  Value formatted as 1.7500E+01
(setq fmtval (rtos x 2 2))     ; Mode 2 = decimal
(princ (strcat str fmtval))    ; displays  Value formatted as 17.50
(setq fmtval (rtos x 3 2))     ; Mode 3 = engineering
(princ (strcat str fmtval))    ; displays  Value formatted as 1'-5.50"
(setq fmtval (rtos x 4 2))     ; Mode 4 = architectural
(princ (strcat str fmtval))    ; displays  Value formatted as 1'-5 1/2"
(setq fmtval (rtos x 5 2))     ; Mode 5 = fractional
(princ (strcat str fmtval))    ; displays  Value formatted as 17 1/2

When the UNOTHODE system variable is set to 1, specifying that units are displayed as entered, the string returned by rtos differs for engineering (mode equals 3), architectural (mode equals 4), and fractional (mode equals 5) units. For example, the first two lines of the preceding sample output would be the same, but the last three lines would appear as follows:

Value formatted as 1'5.50"

Value formatted as 1'5-1/2"

Value formatted as 17-1/2''

Because the angtos function takes the ANGBASE system variable into account, the following code always returns "0":

(angtos (getvar "angbase"))

There is no AutoLISP function that returns a string version (in the current mode/precision) of either the amount of rotation of ANGBASE from true zero (East) or an arbitrary angle in radians.

To find the amount of rotation of ANGBASE from AutoCAD zero (East) or the size of an arbitrary angle, you can do one of the following:

  • Add the desired angle to the current ANGBASE, and then check to see if the absolute value of the result is greater than 2pi; (2 * pi). If so, subtract 2pi;; if the result is negative, add 2pi;, then use the angtos function on the result.
  • Store the value of ANGBASE in a temporary variable, set ANGBASE to 0, evaluate the angtos function, then set ANGBASE to its original value.

Subtracting the result of (atof (angtos 0)) from 360 degrees (2pi; radians or 400 grads) also yields the rotation of ANGBASE from 0.

The distof (distance to floating point) function is the complement of rtos. Therefore, the following calls, which use the strings generated in the previous examples, all return the same value: 17.5. (Note the use of the backslash (\) with modes 3 and 4.)

(distof "1.7500E+01" 1)   ; Mode 1 = scientific
(distof "17.50" 2)        ; Mode 2 = decimal
(distof "1'-5.50\"" 3)    ; Mode 3 = engineering
(distof "1'-5 1/2\"" 4)   ; Mode 4 = architectural
(distof "17 1/2" 5)       ; Mode 5 = fractional

The following code fragments show similar calls to angtos and the values returned (still assuming that DIMZIN equals 0). Precision (the third argument to angtos) is set to 0 places in the first call, 4 places in the next three calls, and 2 places in the last.

(setq ang 3.14159 str2 "\nAngle formatted as ")
(setq fmtval (angtos ang 0 0))   ; Mode 0 = degrees
(princ (strcat str2 fmtval))     ; displays Angle formatted as 180
(setq fmtval (angtos ang 1 4))   ; Mode 1 = deg/min/sec
(princ (strcat str2 fmtval))     ; displays Angle formatted as 180d0'0"
(setq fmtval (angtos ang 2 4))   ; Mode 2 = grads
(princ (strcat str2 fmtval))     ; displays Angle formatted as 200.0000g
(setq fmtval (angtos ang 3 4))   ; Mode 3 = radians
(princ (strcat str2 fmtval))     ; displays Angle formatted as 3.1416r
(setq fmtval (angtos ang 4 2))   ; Mode 4 = surveyor's
(princ (strcat str2 fmtval))     ; displays Angle formatted as W

The UNITHODE system variable also affects strings returned by angtos when it returns a string in surveyor's units (mode equals 4). If UNITMODE equals 0, the string returned can include spaces (for example, "N 45d E"); if UNITMODE equals 1, the string contains no spaces (for example, "N45dE").

The angtof function complements angtos, so all of the following calls return the same value: 3.14159.

(angtof "180" 0)          ; Mode 0 = degrees
(angtof "180d0'0\"" 1)    ; Mode 1 = deg/min/sec
(angtof "200.0000g" 2)    ; Mode 2 = grads
(angtof "3.14159r" 3)     ; Mode 3 = radians
(angtof "W" 4)            ; Mode 4 = surveyor's

When you have a string specifying a distance in feet and inches, or an angle in degrees, minutes, and seconds, you must precede the quotation mark with a backslash (\") so it doesn't look like the end of the string. The preceding examples of angtof and distof demonstrate this action.


Angular Conversion

String Conversions
Conversions
ASCII Code Conversion
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions >
Angular Conversion

If your application needs to convert angular values from radians to degrees, you can use the angtos function, which returns a string, and then convert that string into a floating point value with atof.

(setq pt1 '(1 1) pt2 '(1 2))
(setq rad (angle pt1 pt2))
(setq deg (atof (angtos rad 0 2)))         returns    90.0

However, a more efficient method might be to include a Radian->Degrees function in your application. The following code shows this:

; Convert value in radians to degrees
(defun Radian->Degrees (nbrOfRadians)
  (* 180.0 (/ nbrOfRadians pi))
)

After this function is defined, you can use the Radian->Degrees function throughout your application, as in

(setq degrees (Radian->Degrees rad))      returns    90.0

You may also need to convert from degrees to radians. The following code shows this:

; Convert value in degrees to radians
(defun Degrees->Radians (numberOfDegrees)
  (* pi (/ numberOfDegrees 180.0))
) ;_ end of defun


ASCII Code Conversion

Angular Conversion
Conversions
Unit Conversion
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions >
ASCII Code Conversion

AutoLISP provides the ascii and chr functions that handle decimal ASCII codes. The ascii function returns the ASCII decimal value associated with a string, and chr returns the character associated with an ASCII decimal value.

To see your system's characters with their codes in decimal, octal, and hexadecimal form, save the following AutoLISP code to a file named ascii.lsp. Then load the file and enter the new ASCII command at the AutoCAD Command prompt. This command prints the ASCII codes to the screen and to a file called ascii.txt. The C:ASCII function makes use of the BASE function. You may find this conversion utility useful in other applications.

; BASE converts from a decimal integer to a string in another base.
(defun BASE ( bas int / ret yyy zot )
  (defun zot ( i1 i2 / xxx )
    (if (> (setq xxx (rem i2 i1)) 9)
      (chr (+ 55 xxx))
      (itoa xxx)
    )
  )
  (setq ret (zot bas int) yyy (/ int bas))
  (while (>= yyy bas)
    (setq ret (strcat (zot bas yyy) ret))
    (setq yyy (/ yyy bas))
  )
  (strcat (zot bas yyy) ret)
)
(defun C:ASCII ( / chk out ct code dec oct hex )
  (initget "Yes")
  (setq chk (getkword "\nWriting to ASCII.TXT, continue? <Y>: "))
  (if (or (= chk "Yes")(= chk nil))    (progn
      (setq out (open "ascii.txt" "w") chk 1 code 0 ct 0)
      (princ "\n \n CHAR   DEC  OCT  HEX \n")
      (princ "\n \n CHAR   DEC  OCT  HEX \n" out)
      (while chk
        (setq dec (strcat "  " (itoa code))
          oct (base 8 code) hex (base 16 code))
        (setq dec (substr dec (- (strlen dec) 2) 3))
        (if (< (strlen oct) 3)(setq oct (strcat "0" oct)))
        (princ (strcat "\n " (chr code) "      " dec " "
          oct "  " hex ) )
        (princ (strcat "\n " (chr code) "      " dec " "
          oct "  " hex ) out)
        (cond
          ((= code 255)(setq chk nil))
          ((= ct 20)
            (setq xxx (getstring
               "\n \nPress 'X' to eXit or any key to continue: "))
            (if (= (strcase xxx) "X")
              (setq chk nil)
              (progn
                (setq ct 0)
                (princ "\n \n CHAR   DEC  OCT  HEX \n")
              )
            )
          )
        )
        (setq ct (1+ ct) code (1+ code))
      )
      (close out)
      (setq out nil)
    )
  )
  (princ)
)


Unit Conversion

ASCII Code Conversion
Conversions
Converting from Inches to Meters
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions >
Unit Conversion

The acad.unt file defines various conversions between real-world units such as miles to kilometers, Fahrenheit to Celsius, and so on. The function cvunit takes a value expressed in one system of units and returns the equivalent value in another system. The two systems of units are specified by strings containing expressions of units defined in acad.unt.

The cvunit function does not convert incompatible dimensions. For example, it does not convert inches into grams.

The first time cvunit converts to or from a unit during a drawing editor session, it must look up the string that specifies the unit in acad.unt. If your application has many values to convert from one system of units to another, it is more efficient to convert the value 1.0 by a single call to cvunit and then use the returned value as a scale factor in subsequent conversions. This works for all units defined in acad.unt, except temperature scales, which involve an offset as well as a scale factor.

Topics in this section

  • Converting from Inches to Meters
  • The Unit Definition File


Converting from Inches to Meters

Unit Conversion
Unit Conversion
The Unit Definition File
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions > Unit Conversion >
Converting from Inches to Meters

If the current drawing units are engineering or architectural (feet and inches), the following routine converts a user-specified distance of inches into meters:

(defun C:I2M ( / eng_len metric_len eng metric)
  (princ "\nConverting inches to meters. ")
  (setq eng_len
    (getdist "\nEnter a distance in inches: "))
  (setq metric_len  (cvunit eng_len "inches" "meters"))
  (setq eng (rtos eng_len 2 4)
        metric (rtos metric_len 2 4))
  (princ
    (strcat "\n\t" eng " inches = " metric " meters."))
  (princ)
)


The Unit Definition File

Converting from Inches to Meters
Unit Conversion
Coordinate System Transformations
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions > Unit Conversion >
The Unit Definition File

With the AutoCAD unit definition file acad.unt, you can define factors to convert data in one set of units to another set of units. The definitions in acad.unt are in ASCII format and are used by the unit-conversion function cvunit.

You can make new units available by using a text editor to add their definitions to acad.unt. A definition consists of two lines in the file—the unit name and the unit definition. The first line must have an asterisk (*) in the first column, followed by the name of the unit. A unit name can have several abbreviations or alternate spellings, separated by commas. If a unit name has singular and plural forms, you can specify these using the following format:

*[ [common] [ ( [singular.] plural) ] ]...

You can specify multiple expressions (singular and plural). They don't have to be located at the end of the word, and a plural form isn't required. The following are examples of valid unit name definitions:

*inch(es)
*milleni(um.a)
*f(oot.eet) or (foot.feet)

The line following the *unit name line defines the unit as either fundamental or derived.

Fundamental Units

A fundamental unit is an expression in constants. If the line following the *unit name line begins with something other than an equal sign (=), it defines fundamental units. Fundamental units consist of five integers and two real numbers in the following form:

c, e, h, k, m, r1, r2

The five integers correspond to the exponents of these five constants:

c Velocity of light in a vacuum

e Electron charge

h Planck's constant

k Boltzman's constant

m Electron rest mass

As a group, these exponents define the dimensionality of the unit: length, mass, time, volume, and so on.

The first real number (r1) is a multiplier, and the second (r2) is an additive offset (used only for temperature conversions). The fundamental unit definition allows for different spellings of the unit (for example, meter and metre); the case of the unit is ignored. An example of a fundamental unit definition is as follows:

*meter(s),metre(s),m
-1,0,1,0,-1,4.1214856408e11,0

In this example, the constants that make one meter are as follows:

Derived Units

A derived unit is defined in terms of other units. If the line following the *unit name line begins with an equal sign (=), it defines derived units. Valid operators in these definitions are * (multiplication), / (division), + (addition), - (subtraction), and ^ (exponentiation). You can specify a predefined unit by naming it, and you can use abbreviations (if provided). The items in a formula are multiplied together unless some other arithmetic operator is specified. For example, the units database defines the dimensionless multiple and submultiple names, so you can specify a unit such as micro-inches by entering micro inch. The following are examples of derived unit definitions.

; Units of area
*township(s)
=93239571.456 meter^2

The definition of a township is given as 93,239,571.456 square meters.

; Electromagnetic units
*volt(s),v
=watt/ampere

In this example, a volt is defined as a watt divided by an ampere. In the acad.unt, both watts and amperes are defined in terms of fundamental units.

User Comments

To include comments, begin the line with a semicolon. The comment continues to the end of the line.

; This entire line is a comment.

List the acad.unt file itself for more information and examples.


Coordinate System Transformations

The Unit Definition File
Conversions
Point Transformations
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions >
Coordinate System Transformations

The trans function translates a point or a displacement from one coordinate system into another. It takes a point argument, pt, that can be interpreted as either a 3D point or a 3D displacement vector, distinguished by a displacement argument called disp. The disp argument must be nonzero if pt is to be treated as a displacement vector; otherwise, pt is treated as a point. A from argument specifies the coordinate system in which pt is expressed, and a to argument specifies the desired coordinate system. The following is the syntax for the trans function:

(trans pt from to [disp])

The following AutoCAD coordinate systems can be specified by the from and to arguments:

WCS

World coordinate system—the reference coordinate system. All other coordinate systems are defined relative to the WCS, which never changes. Values measured relative to the WCS are stable across changes to other coordinate systems.

UCS

User coordinate system—the working coordinate system. The user specifies a UCS to make drawing tasks easier. All points passed to AutoCAD commands, including those returned from AutoLISP routines and external functions, are points in the current UCS (unless the user precedes them with a * at the Command prompt). If you want your application to send coordinates in the WCS, OCS, or DCS to AutoCAD commands, you must first convert them to the UCS by calling the trans function.

OCS

Object coordinate system—point values returned by entget are expressed in this coordinate system, relative to the object itself. These points are usually converted into the WCS, current UCS, or current DCS, according to the intended use of the object. Conversely, points must be translated into an OCS before they are written to the database by means of the entmod or entmake functions. This is also known as the entity coordinate system.

DCS

Display coordinate system—the coordinate system into which objects are transformed before they are displayed. The origin of the DCS is the point stored in the AutoCAD system variable TARGET, and its Z axis is the viewing direction. In other words, a viewport is always a plan view of its DCS. These coordinates can be used to determine where something will be displayed to the AutoCAD user.

When the from and to integer codes are 2 and 3, in either order, 2 indicates the DCS for the current model space viewport and 3 indicates the DCS for paper space (PSDCS). When the 2 code is used with an integer code other than 3 (or another means of specifying the coordinate system), it is assumed to indicate the DCS of the current space, whether paper space or model space. The other argument is also assumed to indicate a coordinate system in the current space.

PSDCS

Paper space DCS—this coordinate system can be transformed only to or from the DCS of the currently active model space viewport. This is essentially a 2D transformation, where the X and Y coordinates are always scaled and are offset if the disp argument is 0. The Z coordinate is scaled but is never translated. Therefore, it can be used to find the scale factor between the two coordinate systems. The PSDCS (integer code 2) can be transformed only into the current model space viewport. If the from argument equals 3, the to argument must equal 2, and vice versa.

Both the from and to arguments can specify a coordinate system in any of the following ways:

  • As an integer code that specifies the WCS, current UCS, or current DCS (of either the current viewport or paper space).
  • As an entity name returned by one of the entity name or selection set functions described in Using AutoLISP to Manipulate AutoCAD Objects This specifies the OCS of the named object. For planar objects, the OCS can differ from the WCS, as described in the AutoCAD User's Guide. If the OCS does not differ, conversion between OCS and WCS is an identity operation.
  • As a 3D extrusion vector. Extrusion vectors are always represented in World coordinates; an extrusion vector of (0,0,1) specifies the WCS itself.

The following table lists the valid integer codes that can be used as the to and from arguments:

Coordinate system codes
Code | Coordinate system
0 | World (WCS)
1 | User (current UCS)
2 | Display; DCS of current viewport when used with code 0 or 1, DCS of current model space viewport when used with code 3
3 | Paper space DCS, PSDCS (used only with code 2)

The following example translates a point from the WCS into the current UCS.

(setq pt '(1.0 2.0 3.0))
(setq cs_from 0)              ; WCS
(setq cs_to 1)                ; UCS
(trans pt cs_from cs_to 0)    ; disp
= 0 indicates that pt is a point

If the current UCS is rotated 90 degrees counterclockwise around the World Z axis, the call to trans returns a point (2.0,-1.0,3.0). However, if you swap the to and from values, the result differs as shown in the following code:

(trans pt cs_to cs_from 0) ; the
result is (-2.0,1.0,3.0)

Topics in this section

  • Point Transformations


Point Transformations

Coordinate System Transformations
Coordinate System Transformations
File Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Conversions > Coordinate System Transformations >
Point Transformations

If you are doing point transformations with the trans function and you need to make that part of a program run faster, you can construct your own transformation matrix on the AutoLISP side by using trans once to transform each of the basis vectors (0 0 0), (1 0 0), (0 1 0), and (0 0 1). Writing matrix multiplication functions in AutoLISP can be difficult, so it may not be worthwhile unless your program is doing a lot of transformations.


File Handling

Point Transformations
Using AutoLISP to Communicate with AutoCAD
File Search
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
File Handling

AutoLISP provides functions for handling files and data I/O. See File-Handling Functions in AutoLISP Function Synopsis for a complete list of file-handling functions.

Topics in this section

  • File Search
  • Accessing Drawing Properties
  • Accessing Help Files


File Search

File Handling
File Handling
Accessing Drawing Properties
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > File Handling >
File Search

An application can use the findfile function to search for a particular file name. The application can specify the directory to search, or it can use the current AutoCAD library path.

In the following code fragment, findfile searches for the requested file name according to the AutoCAD library path:

(setq refname "refc.dwg")
(setq fil  (findfile refname))
(if fil
  (setq refname fil)
  (princ (strcat "\nCould not find file " refname ". " ))
)

If the call to findfile is successful, the variable refname is set to a fully qualified path name string, as follows:

"/home/work/ref/refc.dwg"

When specifying a path name, you must precede the backslash (\)with another backslash so the path name will be recognized by AutoLISP. Alternatively, you can use the slash character (/) as a directory separator.

The getfiled function displays a dialog box containing a list of available files of a specified extension type in the specified directory. This gives AutoLISP routines access to the AutoCAD Get File dialog box.

A call to getfiled takes four arguments that determine the appearance and functionality of the dialog box. The application must specify the following string values, each of which can be nil: a title, placed at the top of the dialog box; a default file name, displayed in the edit box at the bottom of the dialog box; and an extension type, which determines the initial files provided for selection in the list box. The final argument is an integer value that specifies how the dialog box interacts with selected files.

This simple routine uses getfiled to let you view your directory structure and select a file:

(defun C:DDIR ( )
  (setq dfil (getfiled "Directory Listing" "" "" 2))
  (princ (strcat "\nVariable 'dfil' set to selected file " dfil ))
  (princ)
)

This is a useful utility command. The dfil variable is set to the file you select, which can then be used by other AutoLISP functions or as a response to a command line prompt for a file name. To use this variable in response to a command line prompt, enter !dfil.

NoteYou cannot use !dfil in a dialog box. It is valid only at the command line.

For more information, see getfiled in the AutoLISP Reference.


Accessing Drawing Properties

File Search
File Handling
Accessing Help Files
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > File Handling >
Accessing Drawing Properties

To access drawing properties such as Title, Subject, Author, and Keywords, use the IAcadSummaryInfo interface. This interface is accessible as a property of the Document object in the AutoCAD object model.

In the following example, the IAcadSummaryInfo interface is used to add standard and custom properties to a drawing named MyDrawing.dwg:

(vl-load-com)
(defun c:ADD_PROPS (/ doc db si author nc nc2 nc3 value3 value4)
  (setq doc (vla-get-ActiveDocument (vlax-get-Acad-Object)))
  (setq db (vla-get-Database doc))
  (setq si (vla-get-SummaryInfo db))
  (vla-put-author si "John")
  (vla-put-comments si "New comments")
  (vla-put-hyperlinkbase si "http://AddURL")
  (vla-put-keywords si "New keywords")
  (vla-AddCustomInfo si "siPutKey" "siPutValue")
  (setq nc (vla-numcustominfo si))
  (vla-SetCustomByKey si "siPutKey" "siPutValueByKey")
  (vla-GetCustomByKey si "siPutKey" 'value3)
  (if (/= "siPutValueByKey" value3)
    (princ "*** Error SetCustomByKey\n")
  )
  (vla-SetCustomByIndex si (1- nc) "siPutCustomByIndexKey"
    "siPutCustomByIndexValue")
  (vla-GetCustomByKey si "siPutCustomByIndexKey" 'value4)
  (if (/= "siPutCustomByIndexValue" value4)
    (princ "*** Error SetCustomByIndex\n")
  )
  (vla-RemoveCustomByIndex si (1- nc))
  (setq nc2 (vla-numcustominfo si))
  (if (/= nc2 (1- nc))
    (princ "*** Error RemoveCustomByIndex")
  )
  (vla-AddCustomInfo si "siPutKey" "siPutValue")
  ; Remove property
  (vla-RemoveCustomByKey si "siPutKey")
  (setq nc3 (vla-numcustominfo si))
  (if (/= nc2 (1- nc))
    (princ "*** Error RemoveCustomByKey")
  )
  (vla-AddCustomInfo si "siPutKey" "siPutValue")
  (vlax-release-object si)
  (vlax-release-object db)
  (vlax-release-object doc)
  (princ)
)
(princ)
Drawing properties can be
read using the same inteface, the IAcadSummaryInfo interface,
as in the following example:
(vl-load-com)
(defun c:GET_PROPS (/ doc db si author )
  (if (/= "MyDrawing.dwg" (getvar "DWGNAME"))
    (princ "Open MyDrawing.dwg")
    (progn
      (setq doc (vla-get-ActiveDocument (vlax-get-Acad-Object)))
      (setq db (vla-get-Database doc))
      (setq si (vla-get-SummaryInfo db))
      (princ "\nAuthor: \n")
      (if (/= "John" (setq author (vla-get-author si)))
        (princ "*** vla-get-author error")
        (princ author)
    )
    (princ "\n")
    (princ "\nComments:\n ")
    (princ (vla-get-comments si))
    (princ "\n")
    (princ "\nHyperlink-base: \n")
    (princ (vla-get-HyperlinkBase si))
    (princ "\n")
    (princ "\nNumber of custom properties: ")
    (princ (setq nc (vla-numcustominfo si)))
    (princ "\n")
    (while (> nc 0)
      (princ "Custom property ")
      (princ nc)
      (vla-GetCustomByIndex si (- nc 1) 'key 'value)
      (princ ": key(")
      (princ key)
      (princ ")")
      (princ " value(")
      (princ value)
      (princ ")\n")
      (vla-GetCustomByKey si key 'value2)
      (if (/= value value2)
        (princ "\n*** Error GetCustomByKey returned unexpected
         result.\n")
      )
      (setq nc (1- nc))
    )
    (vlax-release-object si)
    (vlax-release-object db)
    (vlax-release-object doc)
    )
  )
  (princ)
)
For more information on the
properties and methods used to access drawing properties, see the ActiveX and VBA Reference.


Accessing Help Files

Accessing Drawing Properties
File Handling
Device Access and Control
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > File Handling >
Accessing Help Files

The help function provides access to both AutoCAD Help files (.ahp) and Windows Help files (.hlp). Depending on the Help file's extension, the help function calls the AutoCAD or the Windows Help viewer with the specified file. You can use this function to add a Help facility to your applications. The following code fragment calls the default AutoCAD Help file and provides information about the LINE command.

(help "" "line")

You can create a Help file that provides information about your applications or about procedures you use in your business. The following user-defined command displays the morehelp.hlp Help file as follows:

(defun C:MYHELP ( )
  (help "morehelp.hlp")
  (princ)
)

See the Customization Guide for information on creating and modifying help files.

The setfunhelp function provides help for user-defined commands. After the definition of your new command, adding a call to setfunhelp associates a specific help file and topic with that command. The following example assigns the help topic “Mycmd” in the file morehelp.hlp to the user-defined MYCMD command:

(defun C:MYCMD ( )
  .
  . Command definition
  .
)
(setfunhelp c:mycmd "morehelp.hlp" "mycmd")


Device Access and Control

Accessing Help Files
Using AutoLISP to Communicate with AutoCAD
Accessing User Input
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD >
Device Access and Control

AutoLISP provides the grread and tablet functions for accessing data from the various input devices.

Note that the read-char and read-line file-handling functions can also read input from the keyboard input buffer. See the AutoLISP Reference for more information on these functions.

Topics in this section

  • Accessing User Input
  • Calibrating Tablets


Accessing User Input

Device Access and Control
Device Access and Control
Calibrating Tablets
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Device Access and Control >
Accessing User Input

The grread function returns raw user input, whether from the keyboard or from the pointing device (mouse or digitizer). If the call to grread enables tracking, the function returns a digitized coordinate that can be used for things such as dragging.

NoteThere is no guarantee that applications calling grread will be upward compatible. Because it depends on the current hardware configuration, applications that call grread are not likely to work in the same way on all configurations.


Calibrating Tablets

Accessing User Input
Device Access and Control
Using AutoLISP to Manipulate AutoCAD Objects
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Communicate with AutoCAD > Device Access and Control >
Calibrating Tablets

AutoCAD users can calibrate a digitizing tablet by using the TABLET command (see the Command Reference for a description of this command). The tablet function enables applications to manage calibration by setting the calibrations directly and by saving those settings for future use.

The first argument to the tablet function is an integer code. If code is equal to 0, the function returns the current calibration. If code is equal to 1, the calibration is set according to the remaining arguments. Calibrations are expressed as four 3D points (in addition to the code). The first three points—row1, row2, and row3—are the three rows of the tablet's transformation matrix. The fourth point, direction, is a vector that is normal to the plane in which the tablet's surface is assumed to lie (expressed in WCS, the World Coordinate System). When the calibration is set with the TABLET command, the tablet's surface is assumed to lie in the XY plane of the current UCS.

NoteThe TABMODE system variable controls whether Tablet mode is turned on (1) or off (0). You can control it by using the setvar function.

The following sample routine retrieves the current tablet calibration and stores it in the variable tcal:

(defun C:TABGET ( )
  (setq tcal (tablet 0))
  (if tcal
    (princ
      (strcat "\nConfiguration saved, "
        "use TABSET to retrieve calibration.")
    )
    (princ "\nCalibration not obtainable ")
  )
  (princ)
)

If the preceding routine was successful, the symbol tcal now contains the list returned by the tablet function. This list might appear as follows:

(1 (0.00561717 -0.000978942 -7.5171)
  (0.000978942 0.00561717 -9.17308)
  (0.0 0.0 1.0)
  (0.0 0.0 1.0)
)

To reset the calibration to the values retrieved by the preceding routine, you can use the C:TABSET routine, as follows:

(defun C:TABSET ( )
  (if (not  (apply 'tablet tcal))
    (princ "\nUnable to reset calibration. ")
    (progn
      (princ "\nTablet calibration reset. ")
      (setvar "tabmode" 1)
      (if (= (getvar "tabmode") 0)
        (princ "\nUnable to turn on tablet mode ")
      )
    )
  )
  (princ)
)

The transformation matrix passed as row1, row2, and row3 is a 3×3 transformation matrix that is meant to transform a 2D point. The 2D point is expressed as a column vector in homogeneous coordinates (by appending 1.0 as the third element), so the transformation looks like this:

The calculation of a point is similar to the 3D case. AutoCAD transforms the point by using the following formulas:

To turn the resulting vector back into a 2D point, the first two components are divided by the third component (the scale factor D') yielding the point (X'/D',Y'/D').

For projective transformations, the most general case, tablet does the full calculation. But for affine and orthogonal transformations, M20 and M21 are both 0, so D' would be 1.0. The calculation of D' and the division are omitted; the resulting 2D point is simply (X',Y').

As the previous paragraph implies, an affine transformation is a special, uniform case of a projective transformation. An orthogonal transformation is a special case of an affine transformation: not only are M20 and M21 zero, but M00 = M11 and M10 = -M01.

NoteWhen you set a calibration, the list returned does not equal the list provided if the direction isn't normalized. AutoCAD normalizes the direction vector before it returns it. Also, it ensures the third element in the third column (row3[Z]) is equal to 1. This situation should not arise if you set the calibration by using values retrieved from AutoCAD by means of tablet. However, it can happen if your program calculates the transformation itself.


Using AutoLISP to Manipulate AutoCAD Objects

Calibrating Tablets
Using the AutoLISP Language
Selection Set Handling
AutoLISP Developer's Guide > Using the AutoLISP Language >
Using AutoLISP to Manipulate AutoCAD Objects

You can select and handle objects, and use their extended data.

Most AutoLISP® functions that handle selection sets and objects identify a set or an object by the entity name. For selection sets, which are valid only in the current session, the volatility of names poses no problem, but it does for objects because they are saved in the drawing database. An application that must refer to the same objects in the same drawing (or drawings) at different times can use the objects' handles.

AutoLISP uses symbol tables to maintain lists of graphic and non-graphic data related to a drawing, such as the layers, linetypes, and block definitions. Each symbol table entry has a related entity name and handle and can be manipulated in a manner similar to the way other AutoCAD® entities are manipulated.

Topics in this section

  • Selection Set Handling
  • Object Handling
  • Extended Data - xdata
  • Xrecord Objects
  • Symbol Table and Dictionary Access


Selection Set Handling

Using AutoLISP to Manipulate AutoCAD Objects
Using AutoLISP to Manipulate AutoCAD Objects
Selection Set Filter Lists
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects >
Selection Set Handling

AutoLISP provides a number of functions for handling selection sets. For a complete list of selection set functions, see Selection Set Manipulation Functions in AutoLISP Function Synopsis

The ssget function provides the most general means of creating a selection set. It can create a selection set in one of the following ways:

  • Explicitly specifying the objects to select, using the Last, Previous, Window, Implied, WPolygon, Crossing, CPolygon, or Fence options
  • Specifying a single point
  • Selecting the entire database
  • Prompting the user to select objects

With any option, you can use filtering to specify a list of attributes and conditions that the selected objects must match.

NoteSelection set and entity names are volatile. That is, they apply only to the current drawing session.

The first argument to ssget is a string that describes which selection option to use. The next two arguments, pt1 and pt2, specify point values for the relevant options (they should be left out if they don't apply). A point list, pt-list, must be provided as an argument to the selection methods that allow selection by polygons (that is, Fence, Crossing Polygon, and Window Polygon). The last argument, filter-list, is optional. If filter-list is supplied, it specifies the list of entity field values used in filtering. For example, you can obtain a selection set that includes all objects of a given type, on a given layer, or of a given color. Selection filters are described in more detail in Selection Set Filter Lists.

See the ssget entry in the AutoLISP Reference for a list of the available selection methods and the arguments used with each.

The following table shows examples of calls to ssget:

SSGET Examples
Function call | Effect
(setq pt1 '(0.0 0.0 0.0) pt2 '(5.0 5.0 0.0) pt3 '(4.0 1.0 0.0) pt4 '(2.0 6.0 0.0)) | Sets pt1, pt2, pt3, and pt4 to point values
(setq ss1 (ssget)) | Asks the user for a general object selection and places those items in a selection set
(setq ss1 (ssget "P")) | Creates a selection set from the most recently created selection set
(setq ss1 (ssget "L")) | Creates a selection set of the last object added to the database that is visible on the screen
(setq ss1 (ssget pt2)) | Creates a selection set of an object passing through point (5,5)
(setq ss1 (ssget "W" pt1 pt2)) | Creates a selection set of the objects inside the window from (0,0) to (5,5)
(setq ss1 (ssget "F" (list pt2 pt3 pt4))) | Creates a selection set of the objects crossing the fence and defined by the points (5,5), (4,1), and (2,6)
(setq ss1 (ssget "WP" (list pt1 pt2 pt3))) | Creates a selection set of the objects inside the polygon defined by the points (0,0), (5,5), and (4,1)
(setq ss1 (ssget "X")) | Creates a selection set of all objects in the database

When an application has finished using a selection set, it is important to release it from memory. You can do this by setting it to nil:

(setq ss1 nil)

Attempting to manage a large number of selection sets simultaneously is not recommended. An AutoLISP application cannot have more than 128 selection sets open at once. (The limit may be lower on your system.) When the limit is reached, AutoCAD will not create more selection sets. Keep a minimum number of sets open at a time, and set unneeded selection sets to nil as soon as possible. If the maximum number of selection sets is reached, you must call the gc function to free unused memory before another ssget will work.

Topics in this section

  • Selection Set Filter Lists
  • Passing Selection Sets between AutoLISP and ObjectARX Applications


Selection Set Filter Lists

Selection Set Handling
Selection Set Handling
Wild-Card Patterns in Filter Lists
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling >
Selection Set Filter Lists

An entity filter list is an association list that uses DXF group codes in the same format as a list returned by entget. (See the DXF Reference for a list of group codes.) The ssget function recognizes all group codes except entity names (group -1), handles (group 5), and xdata codes (groups greater than 1000). If an invalid group code is used in a filter-list, it is ignored by ssget. To search for objects with xdata, use the -3 code as described in Filtering for Extended Data.

When a filter-list is provided as the last argument to ssget, the function scans the selected objects and creates a selection set containing the names of all main entities matching the specified criteria. For example, you can obtain a selection set that includes all objects of a given type, on a given layer, or of a given color.

The filter-list specifies which property (or properties) of the entities are to be checked and which values constitute a match.

The following examples demonstrate methods of using a filter-list with various object selection options.

SSGET examples using filter lists

Function call

Effect

(setq ss1 (ssget '((0 . "TEXT")))

)

Prompts for general object selection but adds only text objects to the selection set.

(setq ss1 (ssget "P"

'((0 . "LINE")))

)

Creates a selection set containing all line objects from the last selection set created.

(setq ss1 (ssget "W" pt1 pt2

'((8 . "FLOOR9")))

)

Creates a selection set of all objects inside the window that are also on layer FLOOR9.

(setq ss1 (ssget "X"

'((0 . "CIRCLE")))

)

Creates a selection set of all objects in the database that are Circle objects.

(ssget "I" '((0 . "LINE")

(62 . 5)))

Creates a selection set of all blue Line objects that are part of the Implied selection set (those objects selected while PICKFIRST is in effect).

Note that this filter picks up lines that have been assigned color 5 (blue), but not blue lines that have had their color applied by the ByLayer or ByBlock properties.

If both the code and the desired value are known, the list may be quoted as shown previously. If either is specified by a variable, the list must be constructed using the list and cons function. For example, the following code creates a selection set of all objects in the database that are on layer FLOOR3:

(setq lay_name "FLOOR3")
(setq ss1
  (ssget "X"
    (list (cons 8 lay_name))
  )
)

If the filter-list specifies more than one property, an entity is included in the selection set only if it matches all specified conditions, as in the following example:

(ssget "X"  (list  (cons 0 "CIRCLE")(cons 8 lay_name)(cons 62 1)))

This code selects only Circle objects on layer FLOOR3 that are colored red. This type of test performs a Boolean “AND” operation. Additional tests for object properties are described in Logical Grouping of Filter Tests.

The ssget function filters a drawing by scanning the selected entities and comparing the fields of each main entity against the specified filtering list. If an entity's properties match all specified fields in the filtering list, it is included in the returned selection set. Otherwise, the entity is not included in the selection set. The ssget function returns nil if no entities from those selected match the specified filtering criteria.

NoteThe meaning of certain group codes can differ from entity to entity, and not all group codes are present in all entities. If a particular group code is specified in a filter, entities not containing that group code are excluded from the selection set that ssget returns.

When ssget filters a drawing, the selection set it retrieves might include entities from both paper space and model space. However, when the selection set is passed to an AutoCAD command, only entities from the space that is currently in effect are used. (The space to which an entity belongs is specified by the value of its 67 group. Refer to the Customization Guide for further information.)

Topics in this section

  • Wild-Card Patterns in Filter Lists
  • Filtering for Extended Data
  • Relational Tests
  • Logical Grouping of Filter Tests
  • Selection Set Manipulation


Wild-Card Patterns in Filter Lists

Selection Set Filter Lists
Selection Set Filter Lists
Filtering for Extended Data
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling > Selection Set Filter Lists >
Wild-Card Patterns in Filter Lists

Symbol names specified in filtering lists can include wild-card patterns. The wild-card patterns recognized by ssget are the same as those recognized by the wcmatch function, and are described in Wild-Card Matching, and under wcmatch in the AutoLISP Reference.

When filtering for anonymous blocks, you must precede the * character with a reverse single quotation mark (`), also known as an escape character, because the * is read by ssget as a wild-card character. For example, you can retrieve an anonymous block named *U2 with the following:

(ssget "X" '((2 . "`*U2")))


Filtering for Extended Data

Wild-Card Patterns in Filter Lists
Selection Set Filter Lists
Relational Tests
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling > Selection Set Filter Lists >
Filtering for Extended Data

Using the ssgetfilter-list, you can select all entities containing extended data for a particular application. (See Extended Data - xdata.) To do this, use the -3 group code, as shown in the following example:

(ssget "X" '((0 . "CIRCLE") (-3 ("APPNAME"))))

This code will select all circles that include extended data for the "APPNAME" application. If more than one application name is included in the -3 group's list, an AND operation is implied and the entity must contain extended data for all of the specified applications. So, the following statement would select all circles with extended data for both the "APP1" and "APP2" applications:

(ssget "X" '((0 . "CIRCLE") (-3 ("APP1")("APP2"))))

Wild-card matching is permitted, so either of the following statements will select all circles with extended data for either or both of these applications.

(ssget "X" '((0 . "CIRCLE") (-3 ("APP[12]"))))
(ssget "X" '((0 . "CIRCLE") (-3 ("APP1,APP2"))))


Relational Tests

Filtering for Extended Data
Selection Set Filter Lists
Logical Grouping of Filter Tests
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling > Selection Set Filter Lists >
Relational Tests

Unless otherwise specified, an equivalency is implied for each item in the filter-list. For numeric groups (integers, reals, points, and vectors), you can specify other relations by including a special -4 group code that specifies a relational operator. The value of a -4 group is a string indicating the test operator to be applied to the next group in the filter-list.

The following selects all circles with a radius (group code 40) greater than or equal to 2.0:

(ssget "X" '((0 . "CIRCLE") (-4 . ">=") (40 . 2.0)))

The possible relational operators are shown in the following table:

Relational operators for selection set filter lists
Operator | Description
"*" | Anything goes (always true)
"=" | Equals
"!=" | Not equal to
"/=" | Not equal to
"<>" | Not equal to
"<" | Less than
"<=" | Less than or equal to
">" | Greater than
">=" | Greater than or equal to
"&" | Bitwise AND (integer groups only)
"&=" | Bitwise masked equals (integer groups only)

The use of relational operators depends on the kind of group you are testing:

  • All relational operators except for the bitwise operators ("&" and "&=") are valid for both real- and integer-valued groups.
  • The bitwise operators "&" and "&=" are valid only for integer-valued groups. The bitwise AND, "&", is true if ((integer_group & filter) /= 0)—that is, if any of the bits set in the mask are also set in the integer group. The bitwise masked equals, "&=", is true if ((integer_group & filter) = filter)—that is, if all bits set in the mask are also set in the integer_group (other bits might be set in the integer_group but are not checked).
  • For point groups, the X, Y, and Z tests can be combined into a single string, with each operator separated by commas (for example, ">,>,*"). If an operator is omitted from the string (for example, "=,<>" leaves out the Z test), then the “anything goes” operator, "*", is assumed.
  • Direction vectors (group type 210) can be compared only with the operators "*", "=", and "!=" (or one of the equivalent “not equal” strings).
  • You cannot use the relational operators with string groups; use wild-card tests instead.


Logical Grouping of Filter Tests

Relational Tests
Selection Set Filter Lists
Selection Set Manipulation
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling > Selection Set Filter Lists >
Logical Grouping of Filter Tests

You can also test groups by creating nested Boolean expressions that use the logical grouping operators shown in the following table:

Grouping operators for selection set filter lists
Starting operator | Encloses | Ending operator
"<AND" | One or more operands | "AND>"
"<OR" | One or more operands | "OR>"
"<XOR" | Two operands | "XOR>"
"<NOT" | One operand | "NOT>"

The grouping operators are specified by -4 groups, like the relational operators. They are paired and must be balanced correctly in the filter list or the ssget call will fail. An example of grouping operators in a filter list follows:

(ssget "X"
 '(
    (-4 . "<OR")
      (-4 . "<AND")
        (0 . "CIRCLE")
        (40 . 1.0)
      (-4 . "AND>")
      (-4 . "<AND")
        (0 . "LINE")
        (8 . "ABC")
      (-4 . "AND>")
    (-4 . "OR>")
  )
)
This
code selects all circles with a radius of 1.0 plus all lines on
layer "ABC". The grouping
operators are not case-sensitive; for example, you can specify "and>", "<or",
instead of "AND>", "<OR".
Grouping operators are not allowed within the
-3 group. Multiple application names specified in a -3 group use
an implied AND operator. If you want to test for extended data using
other grouping operators, specify separate -3 groups and group them
as desired. To select all circles having extended data for either
application "APP1" or "APP2" but not both, enter the following:
(ssget "X"
 '((0 . "CIRCLE")
    (-4 . "<XOR")
      (-3 ("APP1"))
      (-3 ("APP2"))
    (-4 . "XOR>")
  )
)
You can simplify the coding of frequently used
grouping operators by setting them equal to a symbol. The previous
example could be rewritten as follows (notice that in this example
you must explicitly quote each list):
(setq <xor '(-4 . "<XOR")
       xor> '(-4 . "XOR>") )
(ssget "X"
  (list
    '(0 . "CIRCLE")
    <xor
      '(-3 ("APP1"))
      '(-3 ("APP2"))
    xor>
  )
)
As you
can see, this method may not be sensible for short pieces of code
but can be beneficial in larger applications.


Selection Set Manipulation

Logical Grouping of Filter Tests
Selection Set Filter Lists
Passing Selection Sets between AutoLISP and ObjectARX Applications
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling > Selection Set Filter Lists >
Selection Set Manipulation

Once a selection set has been created, you can add entities to it or remove entities from it with the functions ssadd and ssdel. You can use the ssadd function to create a new selection set, as shown in the following example. The following code fragment creates a selection set that includes the first and last entities in the current drawing (entnext and entlast are described later in this chapter).

(setq fname (entnext))           ; Gets first entity in the
                                 ; drawing.
(setq lname (entlast))           ; Gets last entity in the
                                 ; drawing.
(if (not fname)
  (princ "\nNo entities in drawing. ")
  (progn
    (setq ourset (ssadd fname))  ; Creates a selection set of the
                                 ; first entity.
    (ssadd lname ourset)         ; Adds the last entity to the
                                 ; selection set.
  )
)

The example runs correctly even if only one entity is in the database (in which case both entnext and entlast set their arguments to the same entity name). If ssadd is passed the name of an entity already in the selection set, it ignores the request and does not report an error. The following function removes the first entity from the selection set created in the previous example:

(ssdel fname ourset)

If there is more than one entity in the drawing (that is, if fname and lname are not equal), then the selection set ourset contains only lname, the last entity in the drawing.

The function sslength returns the number of entities in a selection set, and ssmemb tests whether a particular entity is a member of a selection set. Finally, the function ssname returns the name of a particular entity in a selection set, using an index to the set (entities in a selection set are numbered from 0).

The following code shows calls to ssname:

(setq sset (ssget))           ; Prompts the user to create a
                              ; selection set.
(setq ent1 (ssname sset 0))   ; Gets the name of the first
                              ; entity in sset.
(setq ent4 (ssname sset 3))   ; Gets the name of the fourth
                              ; entity in sset.
(if (not ent4)
  (princ "\nNeed to select at least four entities. ")
)
(setq ilast (sslength sset))  ; Finds index of the last entity
                              ; in sset.
                              ; Gets the name of the
                              ; last entity in sset.
(setq lastent (ssname sset (1- ilast)))

Regardless of how entities are added to a selection set, the set never contains duplicate entities. If the same entity is added more than once, the later additions are ignored. Therefore, sslength accurately returns the number of distinct entities in the specified selection set.


Passing Selection Sets between AutoLISP and ObjectARX Applications

Selection Set Manipulation
Selection Set Handling
Object Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Selection Set Handling >
Passing Selection Sets between AutoLISP and ObjectARX Applications

When passing selection sets between AutoLISP and ObjectARX applications, the following should be observed:

If a selection set is created in AutoLISP and stored in an AutoLISP variable, then overwritten by a value returned from an ObjectARX application, the original selection set is eligible for garbage collection (it is freed at the next automatic or explicit garbage collection).

This is true even if the value returned from the ObjectARX application was the original selection set. In the following example, if the adsfunc ObjectARX function returns the same selection set it was fed as an argument, then this selection set will be eligible for garbage collection even though it is still assigned to the same variable.

(setq var1 (ssget))
(setq var1 (adsfunc var1))

If you want the original selection set to be protected from garbage collection, then you must not assign the return value of the ObjectARX application to the AutoLISP variable that already references the selection set. Changing the previous example prevents the selection set referenced by var1 from being eligible for garbage collection.

(setq var1 (ssget))
(setq var2 (adsfunc var1))


Object Handling

Passing Selection Sets between AutoLISP and ObjectARX Applications
Using AutoLISP to Manipulate AutoCAD Objects
Entity Name Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects >
Object Handling

AutoLISP provides functions for handling objects. The object-handling functions are organized into two categories: functions that retrieve the entity name of a particular object, and functions that retrieve or modify entity data. See Object-Handling Functions in AutoLISP Function Synopsis for a complete list of the object-handling functions.

Topics in this section

  • Entity Name Functions
  • Entity Data Functions
  • Entity Data Functions and the Graphics Screen
  • Old-Style Polylines and Lightweight Polylines
  • Non-Graphic Object Handling


Entity Name Functions

Object Handling
Object Handling
Entity Handles and Their Uses
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling >
Entity Name Functions

To operate on an object, an AutoLISP application must obtain its entity name for use in subsequent calls to the entity data or selection set functions. Two functions described in this section, entsel and nentsel, return not only the entity's name but additional information for the application's use.

Both functions require the AutoCAD user to select an object interactively by picking a point on the graphics screen. All the other entity name functions can retrieve an entity even if it is not visible on the screen or if it is on a frozen layer. The entsel function prompts the user to select an object by picking a point on the graphics screen, and entsel returns both the entity name and the value of the point selected. Some entity operations require knowledge of the point by which the object was selected. Examples from the set of existing AutoCAD commands include: BREAK, TRIM, and EXTEND. The nentsel function is described in detail in Entity Context and Coordinate Transform Data. These functions accept keywords if they are preceded by a call to initget.

The entnext function retrieves entity names sequentially. If entnext is called with no arguments, it returns the name of the first entity in the drawing database. If its argument is the name of an entity in the current drawing, entnext returns the name of the succeeding entity.

The following code fragment illustrates how ssadd can be used in conjunction with entnext to create selection sets and add members to an existing set.

(setq e1  (entnext))
(if  (not e1)                ; Sets e1 to name of first entity.
  (princ "\nNo entities in drawing. ")
  (progn
    (setq ss  (ssadd))       ; Sets ss to a null selection set.
    (ssadd e1 ss)            ; Returns selection set ss with
                             ; e1 added.
    (setq e2 (entnext e1))   ; Gets entity following e1.
    (ssadd e2 ss)            ; Adds e2 to selection set ss.
  )
)

The entlast function retrieves the name of the last entity in the database. The last entity is the most recently created main entity, so entlast can be called to obtain the name of an entity that has just been created with a call to command.

You can set the entity name returned by entnext to the same variable name passed to this function. This “walks” a single entity name variable through the database, as shown in the following example:

(setq one_ent (entnext))            ; Gets name of first entity.
 (while one_ent
 .
 .                                  ; Processes new entity.
 .
  (setq one_ent (entnext one_ent))
)                                   ; Value of one_ent is now nil.
Topics in this section
  • Entity Handles and Their Uses
  • Entity Context and Coordinate Transform Data
  • Entity Access Functions


Entity Handles and Their Uses

Entity Name Functions
Entity Name Functions
Entity Context and Coordinate Transform Data
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Name Functions >
Entity Handles and Their Uses

The handent function retrieves the name of an entity with a specific handle. As with entity names, handles are unique within a drawing. However, an entity's handle is constant throughout its life. AutoLISP applications that manipulate a specific database can use handent to obtain the current name of an entity they must use. You can use the DDMODIFY command to get the handle of a selected object.

The following code fragment uses handent to obtain and display an entity name.

(if  (not (setq e1  (handent "5a2")))
  (princ "\nNo entity with that handle exists. ")
  (princ e1)
)

In one particular editing session, this code fragment might display the following:

<Entity name: 60004722>

In another editing session with the same drawing, the fragment might display an entirely different number. But in both cases the code would be accessing the same entity.

The handent function has an additional use. Entities can be deleted from the database with entdel (see Entity Context and Coordinate Transform Data). The entities are not purged until the current drawing ends. This means that handent can recover the names of deleted entities, which can then be restored to the drawing by a second call to entdel.

NoteHandles are provided for block definitions, including subentities.

Entities in drawings that are cross-referenced by way of XREF Attach are not actually part of the current drawing; their handles are unchanged but cannot be accessed by handent. However, when drawings are combined by means of INSERT, INSERT *, XREF Bind (XBIND), or partial DXFIN, the handles of entities in the incoming drawing are lost, and incoming entities are assigned new handle values to ensure each handle in the current drawing remains unique.


Entity Context and Coordinate Transform Data

Entity Handles and Their Uses
Entity Name Functions
Entity Access Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Name Functions >
Entity Context and Coordinate Transform Data

The nentsel and nentselp functions are similar to entsel, except they return two additional values to handle entities nested within block references.

Another difference between these functions is that when the user responds to a nentsel call by selecting a complex entity or a complex entity is selected by nentselp, these functions return the entity name of the selected subentity and not the complex entity's header, as entsel does.

For example, when the user selects a 3D polyline, nentsel returns a vertex subentity instead of the polyline header. To retrieve the polyline header, the application must use entnext to step forward to the seqend subentity, and then obtain the name of the header from the seqend subentity's -2 group. The same applies when the user selects attributes in a nested block reference.

Selecting an attribute within a block reference returns the name of the attribute and the pick point. When the selected object is a component of a block reference other than an attribute, nentsel returns a list containing the following elements:

  • The selected entity's name.
  • A list containing the coordinates of the point used to pick the object.
  • The Model to World Transformation Matrix. This is a list consisting of four sublists, each of which contains a set of coordinates. This matrix can be used to transform the entity definition data points from an internal coordinate system called the model coordinate system (MCS), to the World Coordinate System (WCS). The insertion point of the block that contains the selected entity defines the origin of the MCS. The orientation of the UCS when the block is created determines the direction of the MCS axes.
  • A list containing the entity name of the block that contains the selected object. If the selected object is in a nested block (a block within a block), the list also contains the entity names of all blocks in which the selected object is nested, starting with the innermost block and continuing outward until the name of the block that was inserted in the drawing is reported.

The list returned from selecting a block with nentsel is summarized as follows:

(<Entity Name: ename1>     ; Name of entity.
  (Px Py Pz)               ; Pick point.
  ( (X0 Y0 Z0)             ; Model to World Transformation Matrix.
    (X1 Y1 Z1)
    (X2 Y2 Z2)
    (X3 Y3 Z3)
  )
  (<Entity name: ename2>   ; Name of most deeply nested block
     .                     ; containing selected object.
     .
     .
  <Entity name: enamen>)   ; Name of outermost block
)                          ; containing selected object.

In the following example, create a block to use with the nentsel function.

Command: line

Specify first point:  1,1

Specify next point or [Undo]:  3,1

Specify next point or [Undo]:  3,3

Specify next point or [Close/Undo]:  1,3

Specify next point or [Close/Undo]:  c

Command:  -block

Enter block name or [?]:  square

Specify insertion base point:  2,2

Select objects: Select the four lines you just drew

Select objects: ENTER

Then, insert the block in a UCS rotated 45 degrees about the Z axis:

Command: ucs

Current ucs name: *WORLD*

Enter option[New/Move/orthoGraphic/Prev/Restore/Save/Del/Apply/?/World]

<World>: z

Specify rotation angle about Z axis <0>: 45

Command:  -insert

Enter block name or [?]:  square

Specify insertion point or [Scale/X/Y/Z/Rotate/PScale/PX/PY/PZ/PRotate]:7,0

Enter X scale factor, specify opposite corner, or [Corner/XYZ] <1>: ENTER

Enter Y scale factor <use X scale factor>: ENTER

Specify rotation angle <0>: ENTER

Use nentsel to select the lower-left side of the square.

(setq ndata (nentsel))

This code sets ndata equal to a list similar to the following:

(<Entity Name: 400000a0>     ; Entity name.
 (6.46616 -1.0606 0.0)       ; Pick point.
 ((0.707107 0.707107 0.0)    ; Model to World
  (-0.707107 0.707107 0.0)   ; Transformation Matrix.
  (0.0 -0.0 1.0)
  (4.94975 4.94975 0.0)
 )
 (<Entity name:6000001c>)    ; Name of block containing
                             ; selected object.
)

Once you obtain the entity name and the Model to World Transformation Matrix, you can transform the entity definition data points from the MCS to the WCS. Use entget and assoc on the entity name to obtain the definition points expressed in MCS coordinates. The Model to World Transformation Matrix returned by nentsel is a 4×3 matrix—passed as an array of four points—that uses the convention that a point is a row rather than a column. The transformation is described by the following matrix multiplication:

So the equations for deriving the new coordinates are as follows:

The Mij, where 0 le; i, j le; 2, are the Model to World Transformation Matrix coordinates; X, Y, Z is the entity definition data point expressed in MCS coordinates, and X', Y', Z' is the resulting entity definition data point expressed in WCS coordinates.

To transform a vector rather than a point, do not add the translation vector (M30 M31 M32 from the fourth column of the transformation matrix).

NoteThis is the only AutoLISP function that uses a matrix of this type. The nentselp function is preferred to nentsel because it returns a matrix similar to those used by other AutoLISP and ObjectARX functions .

Using the entity name previously obtained with nentsel, the following example illustrates how to obtain the MCS start point of a line (group code 10) contained in a block definition:

Command: (setq edata (assoc 10 (entget (car ndata))))

(10 -1.0 1.0 0.0)

The following statement stores the Model to World Transformation Matrix sublist in the symbolmatrix.

Command: (setq matrix (caddr ndata))

((0.707107 0.707107 0.0)    ; X transformation
  (-0.707107 0.707107 0.0)  ; Y transformation
  (0.0 -0.0 1.0)            ; Z transformation
  (4.94975 4.94975 0.0)     ; Displacement from WCS origin
)

The following command applies the transformation formula forX ' to change the X coordinate of the start point of the line from an MCS coordinate to a WCS coordinate:

(setq answer
  (+                                        ; add:
    (* (car (nth 0 matrix))(cadr edata))    ; M00 * X
    (* (car (nth 1 matrix))(caddr edata))   ; M10 * Y
    (* (car (nth 2 matrix))(cadddr edata))  ; M20 * Z
    (car (nth 3 matrix))                    ; M30
  )
)

This statement returns 3.53553, the WCSX coordinate of the start point of the selected line.


Entity Access Functions

Entity Context and Coordinate Transform Data
Entity Name Functions
Entity Data Functions
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Name Functions >
Entity Access Functions

The entity access functions are relatively slow. It is best to get the contents of a particular entity (or symbol table entry) once and keep that information stored in memory, rather than repeatedly ask AutoCAD for the same data. Be sure the data remains valid. If the user has an opportunity to alter the entity or symbol table entry, you should reissue the entity access function to ensure the validity of the data.


Entity Data Functions

Entity Access Functions
Object Handling
Deleting an Entity
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling >
Entity Data Functions

The functions described in this section operate on entity data and can be used to modify the current drawing database.

Topics in this section

  • Deleting an Entity
  • Obtaining Entity Information
  • Modifying an Entity
  • Adding an Entity to a Drawing
  • Creating Complex Entities
  • Working with Blocks
  • Anonymous Blocks


Deleting an Entity

Entity Data Functions
Entity Data Functions
Obtaining Entity Information
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Deleting an Entity

The entdel function deletes a specified entity. The entity is not purged from the database until the end of the current drawing session, so if the application calls entdel a second time during that session and specifies the same entity, the entity is undeleted.

Attributes and old-style polyline vertices cannot be deleted independently of their parent entities. The entdel function operates only on main entities. If you need to delete an attribute or vertex, you can use command to invoke the AutoCAD ATTEDIT or PEDIT commands.


Obtaining Entity Information

Deleting an Entity
Entity Data Functions
Modifying an Entity
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Obtaining Entity Information

The entget function returns the definition data of a specified entity. The data is returned as a list. Each item in the list is specified by a DXF group code. The first item in the list contains the entity's current name.

In this example, the following (default) conditions apply to the current drawing:

  • Layer is 0
  • Linetype is CONTINUOUS
  • Elevation is 0

The user has drawn a line with the following sequence of commands:

Command:  line

From point:  1,2

To point:  6,6

To point:  ENTER

An AutoLISP application can retrieve and print the definition data for the line by using the following AutoLISP function:

(defun C:PRINTDXF ( )
  (setq ent (entlast))     ; Set ent to last entity.
  (setq entl (entget ent)) ; Set entl to association list of
                           ; last entity.
  (setq ct 0)              ; Set ct (a counter) to 0.
  (textpage)               ; Switch to the text screen.
  (princ "\nentget of last entity:")
  (repeat (length entl)    ; Repeat for number of members in list:
    (print (nth ct entl))  ; Print a newline, then each list
                           ; member.
    (setq ct (1+ ct))      ; Increments the counter by one.
  )
  (princ)                  ; Exit quietly.
)

This would print the following:

entget of last entity:

(-1 . <Entity name: 1bbd1c8>)

(0 . "LINE")

(330 . <Entity name: 1bbd0c8>)

(5 . "69")

(100 . "AcDbEntity")

(67 . 0)

(410 . "Model")

(8 . "0")

(100 . "AcDbLine")

(10 1.0 2.0 0.0)

(11 6.0 6.0 0.0)

(210 0.0 0.0 1.0)

The -1 item at the start of the list contains the name of the entity. The entmod function, which is described in this section, uses the name to identify the entity to be modified. The individual dotted pairs that represent the values can be extracted by using assoc with the cdr function.

Sublists for points are not represented as dotted pairs like the rest of the values returned. The convention is that the cdr of the sublist is the group's value. Because a point is a list of two or three reals, the entire group is a three- (or four-) element list. The cdr of the group is the list representing the point, so the convention that cdr always returns the value is preserved.

The codes for the components of the entity are those used by DXF. As with DXF, the entity header items (color, linetype, thickness, the attributes-follow flag, and the entity handle) are returned only if they have values other than the default. Unlike DXF, optional entity definition fields are returned whether or not they equal their defaults and whether or not associated X, Y, and Z coordinates are returned as a single point variable, rather than as separate X (10), Y (20), and Z (30) groups.

All points associated with an object are expressed in terms of that object's object coordinate system (OCS). For point, line, 3D line, 3D face, 3D polyline, 3D mesh, and dimension objects, the OCS is equivalent to the WCS (the object points are World points). For all other objects, the OCS can be derived from the WCS and the object's extrusion direction (its 210 group). When working with objects that are drawn using coordinate systems other than the WCS, you may need to convert the points to the WCS or to the current UCS by using the trans function.

When writing functions to process entity lists, make sure the function logic is independent of the order of the sublists; use assoc to guarantee this. The assoc function searches a list for a group of a specified type. The following code returns the object type "LINE" (0) from the list entl.

(cdr (assoc 0 entl))

If the DXF group code specified is not present in the list (or if it is not a valid DXF group), assoc returns nil.

WarningBefore performing an entget on vertex entities, you should read or write the polyline entity's header. If the most recently processed polyline entity is different from the one to which the vertex belongs, width information (the 40 and 41 groups) can be lost.


Modifying an Entity

Obtaining Entity Information
Entity Data Functions
Adding an Entity to a Drawing
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Modifying an Entity

The entmod function modifies an entity. It passes a list that has the same format as a list returned by entget but with some of the entity group values (presumably) modified by the application. This function complements entget. The primary mechanism by which an AutoLISP application updates the database is by retrieving an entity with entget, modifying its entity list, and then passing the list back to the database with entmod.

The following code fragment retrieves the definition data of the first entity in the drawing and changes its layer property to MYLAYER.

(setq en (entnext))     ; Sets en to first entity name
                        ; in the drawing.
(setq ed (entget en))   ; Sets ed to the entity data
                        ; for entity name en.
(setq ed
  (subst  (cons 8 "MYLAYER")
    (assoc 8 ed)        ; Changes the layer group in ed.
    ed                  ; to layer MYLAYER.
  )
)
(entmod ed)             ; Modifies entity en's layer in
                        ; the drawing.

There are restrictions on the changes to the database that entmod can make; entmod cannot change the following:

  • The entity's type or handle.
  • Internal fields. (Internal fields are the values that AutoCAD assigns to certain group codes: -2, entity name reference; -1, entity name; 5, entity handle.) Any attempt to change an internal field—for example, the main entity name in a seqend subentity (group -2)—is ignored.
  • Viewport entities. An attempt to change a viewport entity causes an error.

Other restrictions apply when modifying dimensions and hatch patterns.

AutoCAD must recognize all objects (except layers) that the entity list refers to. The name of any text style, linetype, shape, or block that appears in an entity list must be defined in the current drawing before the entity list is passed to entmod. There is one exception: entmod accepts new layer names.

If the entity list refers to a layer name that has not been defined in the current drawing, entmod creates a new layer. The attributes of the new layer are the standard default values used by the New option of the AutoCAD LAYER command.

The entmod function can modify subentities such as polyline vertices and block attributes.

If you use entmod to modify an entity in a block definition, this affects all INSERT or XREF references to that block. Also, entities in block definitions cannot be deleted by entdel.


Adding an Entity to a Drawing

Modifying an Entity
Entity Data Functions
Creating Complex Entities
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Adding an Entity to a Drawing

An application can add an entity to the drawing database by calling the entmake function. Like that of entmod, the argument to entmake is a list whose format is similar to that returned by entget. The new entity that the list describes is appended to the drawing database (it becomes the last entity in the drawing). If the entity is a complex entity (an old-style polyline or a block), it is not appended to the database until it is complete.

The following code fragment creates a circle on the MYLAYER layer:

(entmake '((0 . "CIRCLE")       ; Object type
          (8 . "MYLAYER")       ; Layer
          (10 5.0 7.0 0.0)      ; Center point
          (40 . 1.0)            ; Radius
) )

The following entmake restrictions apply to all entities:

  • The first or second member in the list must specify the entity type. The type must be a valid DXF group code. If the first member does not specify the type, it can specify only the name of the entity: group -1 (the name is not saved in the database).
  • AutoCAD must recognize all objects that the entity list refers to. There is one exception: entmake accepts new layer names.
  • Any internal fields passed to entmake are ignored.
  • entmake cannot create viewport entities.

For entity types introduced in AutoCAD Release 13 and later releases, you must also specify subclass markers (DXF group code 100) when creating the entity. All AutoCAD entities have the AcDbEntity subclass marker, and this must be explicitly included in the entmake list. In addition, one or more subclass marker entries are required to identify the specific sub-entity type. These entries must follow group code 0 and must precede group codes that are specifically used to define entity properties in the entmake list. For example, the following is the minimum code required to entmake an MTEXT entity:

(entmake '(
 (0 . "MTEXT")
 (100 . "AcDbEntity")   ; Required for all post-R12 entities.
 (8 . "ALAYER")
 (100 . "AcDbMText")    ; Identifies the entity as MTEXT.
 (10 4.0 4.0 0.0)
 (1 . "Some\\Ptext")
 )
)

The following table identifies the entities that do not require subentity marker entries in the list passed to entmake:

DXF names of entities introduced prior to AutoCAD Release 13
3DFACE | ARC
ATTDEF | ATTRIB
CIRCLE | DIMENSION
INSERT | LINE
POINT | POLYLINE (old-style)
SEQEND | SHAPE
SOLID | TEXT
TRACE | VERTEX
VIEWPORT |

The entmake function verifies that a valid layer name, linetype name, and color are supplied. If a new layer name is introduced, entmake automatically creates the new layer. The entmake function also checks for block names, dimension style names, text style names, and shape names, if the entity type requires them. The function fails if it cannot create valid entities. Objects created on a frozen layer are not regenerated until the layer is thawed.


Creating Complex Entities

Adding an Entity to a Drawing
Entity Data Functions
Working with Blocks
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Creating Complex Entities

To create a complex entity (an old-style polyline or a block), you make multiple calls to entmake, using a separate call for each subentity. When entmake first receives an initial component for a complex entity, it creates a temporary file in which to gather the definition data and extended data, if present. (See Extended Data - xdata .) For each subsequent entmake call, the function checks if the temporary file exists. If it does, the new subentity is appended to the file. When the definition of the complex entity is complete (that is, when entmake receives an appropriate seqend or endblk subentity), the entity is checked for consistency; if valid, it is added to the drawing. The file is deleted when the complex entity is complete or when its creation has been canceled.

No portion of a complex entity is displayed on your drawing until its definition is complete. The entity does not appear in the drawing database until the final seqend or endblk subentity has been passed to entmake . The entlast function cannot retrieve the most recently created subentity for a complex entity that has not been completed. You can cancel the creation of a complex entity by entering entmake with no arguments. This clears the temporary file and returns nil.

As the previous paragraphs imply, entmake can construct only one complex entity at a time. If a complex entity is being created andentmake receives invalid data or an entity that is not an appropriate subentity, both the invalid entity and the entire complex entity are rejected. You can explicitly cancel the creation of a complex entity by calling entmake with no arguments.

The following example contains five entmake functions that create a single complex entity, an old-style polyline. The polyline has a linetype of DASHED and a color of BLUE. It has three vertices located at coordinates (1,1,0), (4,6,0), and (3,2,0). All other optional definition data assume default values. (For this example to work properly, the linetype DASHED must be loaded.)

(entmake '((0 . "POLYLINE")    ; Object type
          (62 . 5)             ; Color
          (6 . "dashed")       ; Linetype
          (66 . 1)             ; Vertices follow
) )
(entmake '((0 . "VERTEX")      ; Object type
          (10 1.0 1.0 0.0)     ; Start point
) )
(entmake '((0 . "VERTEX")      ; Object type
          (10 4.0 6.0 0.0)     ; Second point
) )
(entmake '((0 . "VERTEX")      ; Object type
          (10 3.0 2.0 0.0)     ; Third point
) )
(entmake '((0 . "SEQEND")))    ; Sequence end

When defining dotted pairs, as in the above example, there must be a space on both sides of the dot. Otherwise, you will get an invalid dotted pair error message.

Block definitions begin with a block entity and end with an endblk subentity. Newly created blocks are automatically entered into the symbol table where they can be referenced. Block definitions cannot be nested, nor can they reference themselves. A block definition can contain references to other block definitions.

NoteBefore you use entmake to create a block, you should use tblsearch to ensure that the name of the new block is unique. The entmake function does not check for name conflicts in the block definitions table, so it can redefine existing blocks. See Symbol Table and Dictionary Access for information on using tblsearch.

Block references can include an attributes-follow flag (group 66). If present and equal to 1, a series of attribute (attrib) entities is expected to follow the insert object. The attribute sequence is terminated by a seqend subentity.

Old-style polyline entities always include a vertices-follow flag (also group 66). The value of this flag must be 1, and the flag must be followed by a sequence of vertex entities, terminated by a seqend subentity.

Applications can represent polygons with an arbitrarily large number of sides in polyface meshes. However, the AutoCAD entity structure imposes a limit on the number of vertices that a given face entity can specify. You can represent more complex polygons by dividing them into triangular wedges. AutoCAD represents triangular wedges as four-vertex faces where two adjacent vertices have the same value. Their edges should be made invisible to prevent visible artifacts of this subdivision from being drawn. The PFACE command performs this subdivision automatically, but when applications generate polyface meshes directly, the applications must do this themselves.

The number of vertices per face is the key parameter in this subdivision process. The PFACEVMAX system variable provides an application with the number of vertices per face entity. This value is read-only and is set to 4.

Complex entities can exist in either model space or paper space, but not both. If you have changed the current space by invoking either MSPACE or PSPACE (with command ) while a complex entity is being constructed, a subsequent call to entmake cancels the complex entity. This can also occur if the subentity has a 67 group whose value does not match the 67 group of the entity header.


Working with Blocks

Creating Complex Entities
Entity Data Functions
Anonymous Blocks
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Working with Blocks

There is no direct method for an application to check whether a block listed in the BLOCK table is actually referenced by an insert object in the drawing. You can use the following code to scan the drawing for instances of a block reference:

(ssget "x" '((2 . "BLOCKNAME")) )

You must also scan each block definition for instances of nested blocks.


Anonymous Blocks

Working with Blocks
Entity Data Functions
Entity Data Functions and the Graphics Screen
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Entity Data Functions >
Anonymous Blocks

The block definitions (BLOCK) table in a drawing can contain anonymous blocks (also known as unnamed blocks), that AutoCAD creates to support hatch patterns and associative dimensioning. The entmake function can create anonymous blocks other than *Dnnn (dimensions) and *Xnnn (hatch patterns). Unreferenced anonymous blocks are purged from the BLOCK definition table when a drawing is opened. Referenced anonymous blocks (those that have been inserted) are not purged. You can use entmake to create a block reference (insert object) to an anonymous block. (You cannot pass an anonymous block to the INSERT command.) Also, you can use entmake to redefine the block. You can modify the entities in a block (but not the block object itself) with entmod.

The name (group 2) of an anonymous block created by AutoLISP or ObjectARX has the form *Unnn, where nnn is a number generated by AutoCAD. Also, the low-order bit of an anonymous block's block type flag (group 70) is set to 1. When entmake creates a block whose name begins with * and whose anonymous bit is set, AutoCAD treats this as an anonymous block and assigns it a name. Any characters following the * in the name string passed to entmake are ignored.

NoteAnonymous block names do not remain constant. Although a referenced anonymous block becomes permanent, the numeric portion of its name can change between drawing sessions.


Entity Data Functions and the Graphics Screen

Anonymous Blocks
Object Handling
Old-Style Polylines and Lightweight Polylines
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling >
Entity Data Functions and the Graphics Screen

Changes to the drawing made by the entity data functions are reflected on the graphics screen, provided the entity being deleted, undeleted, modified, or made is in an area and on a layer that is currently visible. There is one exception: When entmod modifies a subentity, it does not update the image of the entire (complex) entity. If, for example, an application modifies 100 vertices of an old-style polyline with 100 calls to entmod, the time required to recalculate and redisplay the entire polyline is unacceptably slow. Instead, an application can perform a series of subentity modifications, and then redisplay the entire entity with a single call to the entupd function.

Consider the following: If the first entity in the current drawing is an old-style polyline with several vertices, the following code modifies the second vertex of the polyline and regenerates its screen image.

(setq e1 (entnext))       ; Sets e1 to the polyline's entity name.
(setq v1 (entnext e1))    ; Sets v1 to its first vertex.
(setq v2 (entnext v1))    ; Sets v2 to its second vertex.
(setq v2d (entget v2))    ; Sets v2d to the vertex data.
(setq v2d
  (subst
    '(10 1.0 2.0 0.0)
     (assoc 10 v2d)       ; Changes the vertex's location in v2d
      v2d                 ; to point (1,2,0).
  )
)
(entmod v2d)              ; Moves the vertex in the drawing.
(entupd e1)               ; Regenerates the polyline entity e1.

The argument to entupd can specify either a main entity or a subentity. In either case, entupd regenerates the entire entity. Although its primary use is for complex entities, entupd can regenerate any entity in the current drawing.

NoteTo ensure that all instances of the block references are updated, you must regenerate the drawing by invoking the AutoCAD REGEN command (with command). The entupd function is not sufficient if the modified entity is in a block definition.


Old-Style Polylines and Lightweight Polylines

Entity Data Functions and the Graphics Screen
Object Handling
Processing Curve-Fit and Spline-Fit Polylines
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling >
Old-Style Polylines and Lightweight Polylines

A lightweight polyline (lwpolyline) is defined in the drawing database as a single graphic entity. The lwpolyline differs from the old-style polyline, which is defined as a group of subentities. Lwpolylines display faster and consume less disk space and RAM.

As of Release 14 of AutoCAD, 3D polylines are always created as old-style polyline entities, and 2D polylines are created as lwpolyline entities, unless they are curved or fitted with the PEDIT command. When a drawing from an earlier release is opened in Release 14 or a later release, all 2D polylines convert to lwpolylines automatically, unless they have been curved or fitted or contain xdata.

Topics in this section

  • Processing Curve-Fit and Spline-Fit Polylines


Processing Curve-Fit and Spline-Fit Polylines

Old-Style Polylines and Lightweight Polylines
Old-Style Polylines and Lightweight Polylines
Non-Graphic Object Handling
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Old-Style Polylines and Lightweight Polylines >
Processing Curve-Fit and Spline-Fit Polylines

When an AutoLISP application uses entnext to step through the vertices of an old-style polyline, it might encounter vertices that were not created explicitly. Auxiliary vertices are inserted automatically by the PEDIT command's Fit and Spline options. You can safely ignore them, because changes to these vertices will be discarded the next time the user applies PEDIT to fit or to spline the polyline.

The old-style polyline entity's group 70 flags indicate whether the polyline has been curve-fit (bit value 2) or spline-fit (bit value 4). If neither bit is set, all the polyline's vertices are regular user-defined vertices. However, if the curve-fit bit (2) is set, alternating vertices of the polyline have the bit value 1 set in their 70 group to indicate that they were inserted by the curve-fitting process. If you use entmod to move the vertices of such a polyline with the intent of refitting the curve by means of PEDIT, ignore these vertices.

Likewise, if the old-style polyline entity's spline-fit flag bit (bit 4) is set, an assortment of vertices will be found—some with flag bit 1 (inserted by curve fitting if system variable SPLINESEGS was negative), some with bit value 8 (inserted by spline fitting), and all others with bit value 16 (spline frame-control point). Here again, if you use entmod to move the vertices and you intend to refit the spline afterward, move only the control-point vertices.


Non-Graphic Object Handling

Processing Curve-Fit and Spline-Fit Polylines
Object Handling
Symbol Table Objects
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling >
Non-Graphic Object Handling

AutoCAD uses two types of non-graphical objects: dictionary objects and symbol table objects. Although there are similarities between these object types, they are handled differently.

All object types are supported by the entget, entmod, entdel, and entmake functions, although object types individually dictate their participation in these functions and may refuse any or all processing. With respect to AutoCAD built-in objects, the rules apply for symbol tables and for dictionary objects. For more information, see Symbol Table Objects and Dictionary Objects.

All rules and restrictions that apply to graphic objects apply to non-graphic objects as well. Non-graphic objects cannot be passed to the entupd function.

When using entmake, the object type determines where the object will reside. For example, if a layer object is passed to entmake, it automatically goes to the layer symbol table. If a graphic object is passed to entmake, it will reside in the current space (model or paper).

Topics in this section

  • Symbol Table Objects
  • Dictionary Objects


Symbol Table Objects

Non-Graphic Object Handling
Non-Graphic Object Handling
Dictionary Objects
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Non-Graphic Object Handling >
Symbol Table Objects

The following rules apply to symbol tables:

  • Symbol table entries can be created through entmake with few restrictions, other than being valid record representations, and name conflicts can only occur in the VPORT table. *ACTIVE entries cannot be created.
  • Symbol table entries cannot be deleted with entdel.
  • The object states of symbol tables and symbol table entries may be accessed with entget by passing the entity name. The tblobjname function can be used to retrieve the entity name of a symbol table entry.
  • Symbol tables themselves cannot be created with entmake; however, symbol table entries can be created with entmake.
  • Handle groups (5, 105) cannot be changed in entmod, nor specified in entmake.
  • Symbol table entries that are not in the APPID table can have many of their fields modified with entmod. To be passed to entmod, a symbol table record list must include its entity name, which can be obtained from entget but not from the tblsearch and tblnext functions. The 70 group of symbol table entries is ignored in entmod and entmake operations.

Renaming symbol table entries to duplicate names is not acceptable, except for the VPORT symbol table. The following entries cannot be modified or renamed, except that most LAYER entries can be renamed and xdata can be modified on all symbol table entries.

Symbol table entries that cannot be modified or renamed
Table | Entry name
VPORT | *ACTIVE
LINETYPE | CONTINUOUS
LAYER | Entries cannot be modified, except for xdata, but renaming is allowed

The following entries cannot be renamed, but are otherwise modifiable:

Symbol table entries that cannot be renamed
Table | Entry name
STYLE | STANDARD
DIMSTYLE | STANDARD
BLOCKS | *MODEL_SPACE
BLOCKS | *PAPER_SPACE
APPID | No entries can be renamed


Dictionary Objects

Symbol Table Objects
Non-Graphic Object Handling
Extended Data - xdata
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Object Handling > Non-Graphic Object Handling >
Dictionary Objects

The following rules apply to dictionary objects:

  • Dictionary objects can be examined with entget and their xdata modified with entmod. Their entries cannot be altered with entmod. All access to their entries are made through the dictsearch and dictnext functions.
  • Dictionary entry contents cannot be modified through entmod, although xdata can be modified.
  • Dictionary entries that begin with ACAD* cannot be renamed.


Extended Data - xdata

Dictionary Objects
Using AutoLISP to Manipulate AutoCAD Objects
Organization of Extended Data
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects >
Extended Data - xdata

Several AutoLISP functions are provided to handle extended data (xdata), which is created by applications written with ObjectARX or AutoLISP. If an entity contains xdata, it follows the entity's regular definition data.

You can retrieve an entity's extended data by calling entget. The entget function retrieves an entity's regular definition data and the xdata for those applications specified in the entget call.

When xdata is retrieved with entget, the beginning of extended data is indicated by a -3 code. The -3 code is in a list that precedes the first 1001 group. The 1001 group contains the application name of the first application retrieved, as shown in the table and as described in the topics in this section.

Group codes for regular and extended data
Group code | Field | Type of data
(-1, -2 (0-239 ) | Entity name) Regular definition data fields) . . . | Normal entity definition data
(-3 (1001 (1000, 1002-1071 (1001 (1000, 1002-1071 (1001 | Extended data sentinel Registered application name 1) XDATA fields) . . . Registered application name 2) XDATA fields) . . . Registered application name 3) . . | Extended data

Topics in this section

  • Organization of Extended Data
  • Registration of an Application
  • Retrieval of Extended Data
  • Attachment of Extended Data to an Entity
  • Management of Extended Data Memory Use
  • Handles in Extended Data


Organization of Extended Data

Extended Data - xdata
Extended Data - xdata
Registration of an Application
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Extended Data - xdata >
Organization of Extended Data

Extended data consists of one or more 1001 groups, each of which begins with a unique application name. The xdata groups returned by entget follow the definition data in the order in which they are saved in the database.

Within each application's group, the contents, meaning, and organization of the data are defined by the application. AutoCAD maintains the information but does not use it. The table also shows that the group codes for xdata are in the range 1000-1071. Many of these group codes are for familiar data types, as follows:

String

1000. Strings in extended data can be up to 255 bytes long (with the 256th byte reserved for the null character).

Application Name

1001 (also a string value). Application names can be up to 31 bytes long (the 32nd byte is reserved for the null character) and must adhere to the rules for symbol table names (such as layer names). An application name can contain letters, digits, and the special characters $ (dollar sign), - (hyphen), and _ (underscore). It cannot contain spaces.

Layer Name

1003. Name of a layer associated with the xdata.

Database -Handle

1005. Handle of an entity in the drawing database.

3D Point

1010. Three real values, contained in a point.

Real

1040. A real value.

Integer

1070. A 16-bit integer (signed or unsigned).

Long

1071. A 32-bit signed (long) integer. If the value that appears in a 1071 group is a short integer or real value, it is converted to a long integer; if it is invalid (for example, a string), it is converted to a long zero (0L).

NoteAutoLISP manages 1071 groups as real values. If you use entget to retrieve an entity's definition list that contains a 1071 group, the value is returned as a real, as shown in the following example:

(1071 . 12.0)

If you want to create a 1071 group in an entity with entmake or entmod, you can use either a real or an integer value, as shown in the following example:

(entmake '((..... (1071 . 12) .... )))

(entmake '((..... (1071 . 12.0) .... )))

(entmake '((..... (1071 . 65537.0) .... )))

(entmake '((..... (1071 . 65537) .... )))

But AutoLISP still returns the group value as a real:

(entmake '((..... (1071 . 65537) .... )))

The preceding statement returns the following:

(1071 . 65537.0)

ObjectARX always manages 1071 groups as long integers.

Several other extended data groups have special meanings in this context (if the application chooses to use them):

Control String

1002. An xdata control string can be either "{" or "}". These braces enable the application to organize its data by subdividing it into lists. The left brace begins a list, and the right brace terminates the most recent list. Lists can be nested.

NoteIf a 1001 group appears within a list, it is treated as a string and does not begin a new application group.
Binary Data

1004. Binary data that is organized into variable-length chunks, which can be handled in ObjectARX with the ads_binary structure. The maximum length of each chunk is 127 bytes.

NoteAutoLISP cannot directly handle binary chunks, so the same precautions that apply to long (1071) groups apply to binary groups as well.
World Space Position

1011. Unlike a simple 3D point, the WCS coordinates are moved, scaled, rotated, and mirrored along with the parent entity to which the extended data belongs. The WCS position is also stretched when the STRETCH command is applied to the parent entity and when this point lies within the select window.

World Space -Displacement

1012. A 3D point that is scaled, rotated, or mirrored along with the parent, but not stretched or moved.

World -Direction

1013. A 3D point that is rotated or mirrored along with the parent, but not scaled, stretched, or moved. The WCS direction is a normalized displacement that always has a unit length.

Distance

1041. A real value that is scaled along with the parent entity.

Scale Factor

1042. Also a real value that is scaled along with the parent.

The DXF group codes for xdata are also described in the DXF Reference.


Registration of an Application

Organization of Extended Data
Extended Data - xdata
Retrieval of Extended Data
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Extended Data - xdata >
Registration of an Application

To be recognized by AutoCAD, an application must register the name or names that it uses. Application names are saved with the extended data of each entity that uses them, and also in the APPID table. Registration is done with the regapp function, which specifies a string to use as an application name. If it successfully adds the name to APPID, it returns the name of the application; otherwise it returns nil. A result of nil indicates that the name is already present in the symbol table. This is not an actual error condition but an expected return value, because the application name needs to be registered only once per drawing.

To register itself, an application should first check that its name is not already in the APPID table. If the name is not there, the application must register it. Otherwise, it can simply go ahead and use the data, as described later in this section.

The following fragment shows the typical use of regapp. (The tblsearch function is described in Symbol Table and Dictionary Access.)

(setq appname "MYAPP_2356")        ; Unique application name.
(if  (tblsearch "appid" appname)   ; Checks if already registered.
  (princ (strcat
    "\n" appname " already registered. "))
  (if (=  (regapp appname) nil)    ; Some other problem.
    (princ (strcat
      "\nCan't register XDATA for " appname ". "))
  )
)

The regapp function provides a measure of security, but it cannot guarantee that two separate applications have not chosen the same name. One way of ensuring this is to adopt a naming scheme that uses the company or product name and a unique number (like your telephone number or the current date and time).


Retrieval of Extended Data

Registration of an Application
Extended Data - xdata
Attachment of Extended Data to an Entity
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Extended Data - xdata >
Retrieval of Extended Data

An application can call entget to obtain the xdata that it has registered. The entget function can return both the definition data and the xdata for the applications it requests. It requires an additional argument, application, that specifies the application names. The names passed to entget must correspond to applications registered by a previous call to regapp; they can also contain wild-card characters.

By default, associative hatch patterns contain extended data. The following code shows the association list of this xdata.

Command: (entget (car (entsel)) '("ACAD"))

Select object: Select an associative hatch

Entering the preceding code at the command line returns a list that looks something like this:

((-1 . <Entity name: 600000c0>) (0 . "INSERT") (8 . "0") (2 . "*X0")

(10 0.0 0.0 0.0) (41 . 1.0) (42 . 1.0) (50 . 0.0) (43 . 1.0) (70 . 0) (71 . 0)

(44 . 0.0) (45 . 0.0) (210 0.0 0.0 1.0) (-3 ("ACAD" (1000 . "HATCH")

(1002 . "{") (1070 . 16) (1000 . "LINE") (1040 . 1.0) (1040 . 0.0)

(1002 . "}"))))

This fragment shows a typical sequence for retrieving xdata for two specified applications. Note that the application argument passes application names in list form:

(setq working_elist
  (entget ent_name
    '("MY_APP_1" "SOME_OTHER")  ; Only xdata from "MY_APP_1"
  )                             ; and "SOME_OTHER" is retrieved.
)
(if working_elist
  (progn
    ...                         ; Updates working entity groups.
    (entmod working_elist)      ; Only xdata from registered
  )                             ; applications still in the
)                               ; working_elist list are modified.

As the sample code shows, you can modify xdata retrieved by entget by using a subsequent call to entmod, just as you can use entmod to modify normal definition data. You can also create xdata by defining it in the entity list passed to entmake.

Returning the extended data of only those applications specifically requested protects one application from corrupting another application's data. It also controls the amount of memory that an application needs to use and simplifies the xdata processing that an application needs to perform.

NoteBecause the strings passed by application can include wild-card characters, an application name of "*" will cause entget to return all extended data attached to an entity.


Attachment of Extended Data to an Entity

Retrieval of Extended Data
Extended Data - xdata
Management of Extended Data Memory Use
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Extended Data - xdata >
Attachment of Extended Data to an Entity

You can use xdata to store any type of information you want. For example, draw an entity (such as a line or a circle), then enter the following code to attach xdata to the entity:

(setq lastent (entget (entlast))) ; Gets the association
                                  ; list of definition data
                                  ; for the last entity.
(regapp "NEWDATA")                ; Registers the
                                  ; application name.
(setq exdata                      ; Sets the variable
 '((-3 ("NEWDATA"                 ; exdata equal to the
  (1000 . "This is a new thing!") ; new extended data—
  )))                             ; in this case, a text
)                                 ; string.
(setq newent
  (append lastent exdata))  ; Appends new data list to
                            ; entity's list.
(entmod newent)             ; Modifies the entity with the new
                            ; definition data.

To verify that your new xdata has been attached to the entity, enter the following code and select the object:

(entget (car (entsel)) '("NEWDATA"))

This example shows the basic method for attaching extended data to an entity.


Management of Extended Data Memory Use

Attachment of Extended Data to an Entity
Extended Data - xdata
Handles in Extended Data
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Extended Data - xdata >
Management of Extended Data Memory Use

Extended data is currently limited to 16K per entity. Because the xdata of an entity can be created and maintained by multiple applications, problems can result when the size of the xdata approaches its limit. AutoLISP provides two functions, xdsize and xdroom, to assist in managing the memory that xdata occupies. When xdsize is passed a list of xdata, it returns the amount of memory (in bytes) that the data will occupy. When xdroom is passed the name of an entity, it returns the remaining number of free bytes that can still be appended to the entity.

The xdsize function reads an extended data list, which can be large. This function can be slow, so it is not recommended that you call it frequently. A better approach is to use it (in conjunction with xdroom) in an error handler. If a call to entmod fails, you can use xdsize and xdroom to find out whether the call failed because the entity didn't have enough room for the xdata.


Handles in Extended Data

Management of Extended Data Memory Use
Extended Data - xdata
Xrecord Objects
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Extended Data - xdata >
Handles in Extended Data

Extended data can contain handles (group 1005) to save relational structures within a drawing. One entity can reference another by saving the other's handle in its xdata. The handle can be retrieved later from xdata and then passed to handent to obtain the other entity. Because more than one entity can reference another, xdata handles are not necessarily unique. The AUDIT command does require that handles in extended data either be NULL or valid entity handles (within the current drawing). The best way to ensure that xdata entity handles are valid is to obtain a referenced entity's handle directly from its definition data by means of entget. The handle value is in group 5.

When you reference entities in other drawings (for example, entities that are attached with XREF), you can avoid protests from AUDIT by using extended entity strings (group 1000) rather than handles (group 1005). The handles of cross-referenced entities are either not valid in the current drawing, or they conflict with valid handles. However, if an XREF Attach changes to an XREF Bind or is combined with the current drawing in some other way, it is up to the application to revise the entity references accordingly.

When drawings are combined by means of INSERT, INSERT*, XREF Bind (XBIND), or partial DXFIN, handles are translated so they become valid in the current drawing. (If the incoming drawing did not employ handles, new ones are assigned.) Extended entity handles that refer to incoming entities are also translated when these commands are invoked.

When an entity is placed in a block definition (with the BLOCK command), the entity within the block is assigned new handles. (If the original entity is restored by means of OOPS, it retains its original handles.) The value of any xdata handles remains unchanged. When a block is exploded (with the EXPLODE command), xdata handles are translated in a manner similar to the way they are translated when drawings are combined. If the xdata handle refers to an entity that is not within the block, it is unchanged. However, if the xdata handle refers to an entity that is within the block, the data handle is assigned the value of the new (exploded) entity's handle.


Xrecord Objects

Handles in Extended Data
Using AutoLISP to Manipulate AutoCAD Objects
Symbol Table and Dictionary Access
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects >
Xrecord Objects

Xrecord objects are used to store and manage arbitrary data. They are composed of DXF group codes with normal object groups (that is, non-xdata group codes), ranging from 1 through 369 for supported ranges. These objects are similar in concept to xdata but is not limited by size or order.

The following examples provide methods for creating and listing xrecord data.

(defun C:MAKEXRECORD( / xrec xname )
  ; create the xrecord's data list.
  (setq xrec '((0 . "XRECORD")(100 . "AcDbXrecord")
    (1 . "This is a test xrecord list")
    (10 1.0 2.0 0.0) (40 . 3.14159) (50 . 3.14159)
    (62 . 1) (70 . 180))
  )
  ; use entmakex to create the xrecord with no owner.
  (setq xname (entmakex xrec))
  ; add the new xrecord to the named object dictionary.
  (dictadd (namedobjdict) "XRECLIST" xname)
  (princ)
)
(defun C:LISTXRECORD ( / xlist )
  ; find the xrecord in the named object dictionary.
  (setq xlist (dictsearch (namedobjdict) "XRECLIST"))
  ; print out the xrecord's data list.
  (princ xlist)
  (princ)
)


Symbol Table and Dictionary Access

Xrecord Objects
Using AutoLISP to Manipulate AutoCAD Objects
Symbol Tables
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects >
Symbol Table and Dictionary Access

AutoLISP provides functions for accessing symbol table and dictionary entries. Examples of the tblnext and tblsearch functions are provided in the following sections. For a complete list of the symbol table and dictionary access functions, see Symbol Table and Dictionary-Handling Functions in AutoLISP Function Synopsis Refer to the AutoLISP Reference for more detailed information on the functions listed in the Synopsis.

For additional information on non-graphic objects see, Non-Graphic Object Handling.

Topics in this section

  • Symbol Tables
  • Dictionary Entries


Symbol Tables

Symbol Table and Dictionary Access
Symbol Table and Dictionary Access
Dictionary Entries
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Symbol Table and Dictionary Access >
Symbol Tables

Symbol table entries can also be manipulated by the following functions:

  • entdel
  • entget
  • entmake
  • entmod
  • handent

The tblnext function sequentially scans symbol table entries, and the tblsearch function retrieves specific entries. Table names are specified by strings. The valid names are LAYER, LTYPE, VIEW, STYLE, BLOCK, UCS, VPORT, DIMSTYLE, and APPID. Both functions return lists with DXF group codes that are similar to the entity data returned by entget.

The first call to tblnext returns the first entry in the specified table. Subsequent calls that specify the same table return successive entries, unless the second argument to tblnext (rewind) is nonzero, in which case tblnext returns the first entry again.

In the following example, the function GETBLOCK retrieves the symbol table entry for the first block (if any) in the current drawing, and then displays it in a list format.

(defun C:GETBLOCK (/ blk ct)
  (setq blk (tblnext "BLOCK" 1)) ; Gets the first BLOCK entry.
  (setq ct 0)                    ; Sets ct (a counter) to 0.
  (textpage)                     ; Switches to the text screen.
  (princ "\nResults from GETBLOCK: ")
  (repeat (length blk)           ; Repeats for the number of
                                 ; members in the list.
    (print (nth ct blk))         ; Prints a new line, then
                                 ; each list member.
    (setq ct (1+ ct))            ; Increments the counter by 1.
  )
  (princ)                        ; Exits quietly.
)

Entries retrieved from the BLOCK table contain a -2 group that contains the name of the first entity in the block definition. If the block is empty, this is the name of the block's ENDBLK entity, which is never seen on occupied blocks. In a drawing with a single block named BOX, a call to GETBLOCK displays the following. (The name value varies from session to session.)

Results from GETBLOCK:

(0 . "BLOCK")

(2 . "BOX")

(70 . 0)

(10 9.0 2.0 0.0)

(-2 . <Entity name: 40000126>)

As with tblnext, the first argument to tblsearch is a string that names a table, but the second argument is a string that names a particular symbol in the table. If the symbol is found, tblsearch returns its data. This function has a third argument, setnext, that you can use to coordinate operations with tblnext. If setnext is nil, the tblsearch call has no effect on tblnext, but if setnext is non-nil, the next call to tblnext returns the table entry following the entry found by tblsearch.

The setnext option is useful when you are handling the VPORT symbol table, because all viewports in a particular viewport configuration have the same name (such as *ACTIVE).

If the VPORT symbol table is accessed when TILEMODE is turned off, any changes have no visible effect until TILEMODE is turned on. Do not confuse VPORTS,which is described by the VPORT symbol table with paper space viewport entities.

The following processes all viewports in the 4VIEW configuration:

(setq v (tblsearch "VPORT" "4VIEW" T)) ; Finds first VPORT entry.
(while (and v (= (cdr (assoc 2 v)) "4VIEW"))
  .
  .                                    ; ... Processes entry ...
  .
  (setq v (tblnext "VPORT"))           ; Gets next VPORT entry.
)


Dictionary Entries

Symbol Tables
Symbol Table and Dictionary Access
Accessing AutoCAD Groups
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Symbol Table and Dictionary Access >
Dictionary Entries

A dictionary is a container object, similar to the symbol tables in functions. Dictionary entries can be queried with the dictsearch and dictnext functions. Each dictionary entry consists of a text name key plus a hard ownership handle reference to the entry object. Dictionary entries may be removed by directly passing entry object names to the entdel function. The text name key uses the same syntax and valid characters as symbol table names.

Topics in this section

  • Accessing AutoCAD Groups


Accessing AutoCAD Groups

Dictionary Entries
Dictionary Entries
Working with Programmable Dialog Boxes
AutoLISP Developer's Guide > Using the AutoLISP Language > Using AutoLISP to Manipulate AutoCAD Objects > Symbol Table and Dictionary Access > Dictionary Entries >
Accessing AutoCAD Groups

The following is an example of one method for accessing the entities contained in a group. This example assumes a group named G1 exists in the current drawing.

(setq objdict (namedobjdict))
(setq grpdict (dictsearch objdict "ACAD_GROUP"))

This sets the grpdict variable to the entity definition list of the ACAD_GROUP dictionary and returns the following:

((-1 . <Entity name: 8dc10468>) (0 . "DICTIONARY") (5 . "D")

(102 . "{ACAD_REACTORS") (330 . <Entity name: 8dc10460>)

(102 . "}") (100 . "AcDbDictionary") (3 . "G1")

(350 . <Entity name: 8dc41240>))

The following code sets the variable group1 to the entity definition list of the G1 group:

(setq group1 (dictsearch (cdar grpdict) "G1"))

It returns the following:

((-1 . <Entity name: 8dc10518>) (0 . "GROUP") (5 . "23")

(102 . "{ACAD_REACTORS") (330 . <Entity name: 8dc10468>)

(102 . "}") (100 . "AcDbGroup") (300 . "line and circle") (70 . 0) (71 . 1)

(340 . <Entity name: 8dc10510>)(340 . <Entity name: 8dc10550>) )

The 340 group codes are the entities that belong to the group.


Working with Programmable Dialog Boxes

Accessing AutoCAD Groups
Designing Dialog Boxes
AutoLISP Developer's Guide >
Working with Programmable Dialog Boxes

Topics in this section

  • Designing Dialog Boxes

    With dialog control language, you can create dialog boxes.

  • Managing Dialog Boxes

    You can use dialog boxes to respond to user input.

  • Programmable Dialog Box Reference

    You can use attributes to work with dialog boxes.


Designing Dialog Boxes

Working with Programmable Dialog Boxes
Working with Programmable Dialog Boxes
Dialog Box Components
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes >
Designing Dialog Boxes

With dialog control language, you can create dialog boxes.

Dialog boxes are defined by ASCII files written in dialog control language (DCL). The elements in a dialog box, such as buttons and edit boxes, are known as tiles. The size and functionality of each tile is controlled by the tile's attributes. The size of the dialog box and the layout of its parts are set automatically with a minimum of positioning information. Visual LISP® provides a tool for viewing dialog boxes, and provides functions for controlling dialog boxes from application programs.

This chapter introduces the elements that make up dialog boxes. It explains DCL file structure and syntax, and presents sample AutoLISP® and DCL code for a sample dialog box. This chapter also provides some DCL coding techniques for handling layout problems.

Topics in this section

  • Dialog Box Components
  • Using DCL to Define Dialog Boxes
  • Displaying Dialog Boxes with Visual LISP
  • Adjusting the Layout of Dialog Boxes
  • Design Guidelines


Dialog Box Components

Designing Dialog Boxes
Designing Dialog Boxes
Using DCL to Define Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes >
Dialog Box Components

The following figure shows a standard AutoCAD® dialog box, with some of its components labeled. In dialog box creation and customization these components are known as tiles.

A dialog box consists of the box and the tiles within it. The basic tile types are predefined by the programmable dialog box (PDB) facility.

You can create complex tiles, called subassemblies, by grouping tiles into rows and columns, with or without an enclosing box or border. A row or column of tiles is referred to as a cluster. Subassemblies define groups of tiles or clusters that can be used in many dialog boxes. For example, the OK, Cancel, and Help buttons are grouped into a subassembly, defined as a row (cluster) of three button tiles and some spacing separating the buttons.

Subassemblies are treated as single tiles. The tiles within a subassembly are called children. DCL files are organized in a tree structure. At the top of the tree is a (dialog) tile that defines the dialog box itself. The following diagram shows a DCL file structure:

The layout, appearance, and behavior of a tile or subassembly are specified in DCL by the tile's attributes. For example, the dialog itself, and most predefined tile types, has a label attribute that specifies the text associated with the tile. The label of a dialog box defines the caption at the top of the dialog box, the label of a button specifies the text inside the button, and so on.

DCL also enables you to define new tiles, called prototypes, that are not necessarily associated with a specific dialog box. This is useful when you want to use the same component in several dialog boxes. You can reference prototype tiles from other DCL files and change their attributes the same way you change predefined tiles.

Before you program a dialog box, plan both the dialog box and the application in detail before you code and debug. The sequence in which the data is entered will vary with each user. The need to anticipate a variety of user actions imposes a program structure that is less linear than conventional programming, but is more reflective of the way users work.


Using DCL to Define Dialog Boxes

Dialog Box Components
Designing Dialog Boxes
The base.dcl and acad.dcl Files
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes >
Using DCL to Define Dialog Boxes

You define dialog boxes by entering DCL descriptions in ASCII text files, much like writing AutoLISP code. DCL files have a .dcl extension. A single DCL file can contain the description of one or more dialog boxes, or it can contain only prototype tiles and subassemblies for use by other DCL files. A DCL file consists of the following three parts, which can appear in any order. Depending on your application, only one or more of these parts is required.

  • References to other DCL files

    These consist of include directives as described in Referencing DCL Files.

  • Prototype tile and subassembly definitions

    These are tile definitions you can refer to in subsequent tile definitions (including dialog box definitions).

  • Dialog box definitions

    These define the attributes of tiles or override the attributes defined in prototype tiles and subassemblies.

Topics in this section

  • The base.dcl and acad.dcl Files
  • Referencing DCL Files
  • DCL Syntax


The base.dcl and acad.dcl Files

Using DCL to Define Dialog Boxes
Using DCL to Define Dialog Boxes
Referencing DCL Files
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes >
The base.dcl and acad.dcl Files

The base.dcl and acad.dcl files are included with AutoCAD and are distributed in the User Support folder. To see the path to the User Support folder, from the Tools menu, click Options. On the Files tab, the path to the User Support folder is the first path displayed under Support File Search Path.

The base.dcl file shows the DCL definitions for the basic, predefined tiles and tile types. It also contains definitions for commonly used prototypes. The PDB feature does not allow you to redefine the predefined tiles. The acad.dcl file contains the standard definitions of all the dialog boxes used by AutoCAD.

WarningAny errors in base.dcl may disrupt the appearance of the standard AutoCAD dialog boxes and customized dialog boxes from your application or other applications.


Referencing DCL Files

The base.dcl and acad.dcl Files
Using DCL to Define Dialog Boxes
DCL Syntax
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes >
Referencing DCL Files

When you create dialog boxes, you must create a new, application-specific DCL file. All DCL files can use the tiles defined in the base.dcl file. A DCL file can also use tiles defined in another DCL file by naming the other file in what is called an include directive. You can create your own hierarchy of DCL files, as shown in the following figure:

In this figure, the user1.dcl and user2.dcl files are independent of each other, but user3.dcl uses tiles defined in user1.dcl. The include directive has the form:

@include filename

where filename is a quoted string containing the full name of the other DCL file. For example, the following directive includes a file named usercore.dcl:

@include "usercore.dcl"

If you specify only the file name, the PDB feature searches for the file first in the current directory and then in the same directory as the DCL file itself (the one that contains the include directive). If you specify a full path name, the PDB feature searches only the directory specified in that path.

NoteThe DCL files you create cannot use the dialog boxes defined in acad.dcl. You cannot specify @include"acad.dcl". However, if you want to create similar dialog boxes, you can cut and paste the definitions into your own DCL file.


DCL Syntax

Referencing DCL Files
Using DCL to Define Dialog Boxes
Tile Definitions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes >
DCL Syntax

This section describes the DCL syntax for specifying tiles, tile attributes, and attribute values.

New tiles are created by tile definitions. If a tile definition appears outside a dialog box definition, it is a prototype or a subassembly. Prototypes and subassemblies can be used in dialog box definitions by tile references. Each reference to a definition inherits the attributes of the original tile. When referring to prototypes, you can change the values of the inherited attributes or add new attributes. When referring to subassemblies, you cannot change or add attributes.

If you need multiple instances of a tile with some attributes in common, it is easiest to define and name a prototype that contains only the common attributes. Then, in each reference to the prototype, you can change attributes or add new ones, but you do not have to list all the common attributes each time you reference the tile. Because attributes are inherited, you will more often need to create tile references—especially references to the predefined tiles—than to define new tiles.

Topics in this section

  • Tile Definitions
  • Tile References
  • Attributes and Attribute Values
  • Comments in DCL Files


Tile Definitions

DCL Syntax
DCL Syntax
Tile References
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes > DCL Syntax >
Tile Definitions

Tile definitions have the following form:

name : item1 [ : item2
: item3 ... ] {

     attribute = value;
                 ...
}

where each item is a previously defined tile. The new tile (name) inherits the attributes of all the specified tiles (item1, item2, item3,…). The attribute definitions within the curly braces ({}) either supplement, or, if the attribute's name is identical, replace the inherited definitions. When the definition has multiple parents, attributes take precedence in left-to-right order. In other words, if more than one item specifies the same attribute, the first one encountered is the one used.

If the new definition contains no children, it is a prototype, and you can alter or augment its attributes when referring to it. If it is a subassembly with children, its attributes cannot be altered.

The name of a tile or tile prototype can contain only letters, numbers, or the underscore character (_), and must begin with a letter.

NoteTile names are case-sensitive. For example, bigbutton is not the same as BigButton or BIGBUTTON. Be careful when using capitalization.

This is the (internal) definition of a button:

button : tile {
              fixed_height = true;
              is_tab_stop = true;
}

The base.dcl file defines a default_button as follows:

default_button : button {
              is_default = true;
}

The default_button inherits the button tile's values for the fixed_height and is_tab_stop attributes. It adds a new attribute, is_default, and sets it to true.


Tile References

Tile Definitions
DCL Syntax
Attributes and Attribute Values
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes > DCL Syntax >
Tile References

Tile references have one of the following forms:

name;

or

: name {
attribute = value;
           . . .
}

where name is the name of a previously defined tile. Tile names are case sensitive. In the first instance, all the attributes defined in name are incorporated into the reference. In the second instance, the attribute definitions within the curly braces either supplement or replace the definitions inherited from name. Because this is a tile reference, as opposed to a definition, the attribute changes apply only to this instance of the tile.

NoteThe format of the second instance can refer only to prototypes, not to subassemblies.

The spacer tile is used for layout in a dialog box definition. It has no unique attributes, so references to it specify only its name:

spacer;

The ok_cancel tile defined in base.dcl is a subassembly, so it too can be referenced only by name:

ok_cancel;

On the other hand, you have the option of redefining the attributes of an individual tile. For example, the following statement creates a button with the same properties as a previously defined button, but with different text:

: retirement_button {
       label = "Goodbye";
}

For more information, see Customizing Exit Button Text.


Attributes and Attribute Values

Tile References
DCL Syntax
Comments in DCL Files
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes > DCL Syntax >
Attributes and Attribute Values

Within the curly braces of a tile definition or reference, you specify attributes and assign them values using the following form:

attribute = value ;

where attribute is a valid keyword and value is the value assigned to the attribute. An equal sign (=) separates the attribute from the value, and a semicolon (;) ends the assignment statement. For example, the key attribute defines the name by which a program can refer to the tile, and the label attribute defines the text displayed within the tile. See Synopsis of Predefined Attributes for a complete list of DCL attributes.

As with tile names, attribute names and values are also case-sensitive. Width and width are not the same thing; True and true do not produce the same results.


Comments in DCL Files

Attributes and Attribute Values
DCL Syntax
Displaying Dialog Boxes with Visual LISP
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Using DCL to Define Dialog Boxes > DCL Syntax >
Comments in DCL Files

A statement preceded by two forward slashes (//) is treated as a comment in a DCL file. Anything that appears between the // and the end of the line is ignored. DCL also allows C language style comments. These have the form /*comment text */. The starting /* and ending */ can be on separate lines.


Displaying Dialog Boxes with Visual LISP

Comments in DCL Files
Designing Dialog Boxes
Preview Error Handling
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes >
Displaying Dialog Boxes with Visual LISP

VLISP provides a tool for previewing dialog boxes defined with DCL. To see how this works, copy the following DCL code into a new file in the VLISP text editor:

hello : dialog {
    label = "Sample Dialog Box";
    : text {
      label = "Hello, world";
    }
    : button {
      key = "accept";
      label = "OK";
      is_default = true;
    }
}

This DCL file defines a dialog box labeled “Sample Dialog Box.” It contains a text tile and an OK button. Save the file as hello.dcl, and specify “DCL Source Files” in the Save As Type field of the Save As dialog box.

NoteYou must include the file extension when you specify the file name. VLISP does not automatically add a .dcl file extension for you.

Note how the text editor color codes the statements in the DCL file. The default color coding scheme is shown in the following table:

DCL default color coding
DCL element | Color
Tiles and tile attributes | Blue
Strings | Magenta
Integers | Green
Real numbers | Teal
Comments | Magenta, on gray background
Parentheses | Red
Preprocessor | Dark blue
Operators and punctuation | Dark red
Unrecognized items (for example, user variables) | Black

Choose Tools [image] Interface Tools [image] Preview DCL in Editor to display the dialog box defined in the text editor window. Because you may have more than one dialog box defined in a single .dcl file, VLISP prompts you to specify the name of the dialog you want to view:

If your DCL file contains definitions for multiple dialog boxes, click the pull-down arrow and choose the one you want to preview. There is only one dialog box defined in hello.dcl, so choose OK to view it:

Choose OK to complete previewing the dialog box.

Although buttons are a good way to demonstrate dialog box attributes, there are standard exit button subassemblies you should use in your dialog boxes. You can create a dialog box that is virtually the same as the one shown in the previous figure by using the ok_only subassembly. See Dialog Box Exit Buttons and Error Tiles.

Topics in this section

  • Preview Error Handling
  • Semantic Auditing of DCL Files


Preview Error Handling

Displaying Dialog Boxes with Visual LISP
Displaying Dialog Boxes with Visual LISP
Semantic Auditing of DCL Files
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Displaying Dialog Boxes with Visual LISP >
Preview Error Handling

If your DCL code contains errors, the VLISP DCL previewer displays messages indicating the offending line and keyword or symbol. For example, introduce an error into hello.dcl by removing the colon before “button,” then try previewing the dialog box. You'll see the following message:

Choose OK to clear the message from your screen. VLISP may display additional error messages, like the following:


Semantic Auditing of DCL Files

Preview Error Handling
Displaying Dialog Boxes with Visual LISP
Adjusting the Layout of Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Displaying Dialog Boxes with Visual LISP >
Semantic Auditing of DCL Files

AutoCAD provides a choice of four levels (0-3) of semantic auditing for DCL files (see the following table). Auditing attempts to detect code in the DCL file that is likely to be problematic or unnecessary. These audits are done at DCL load time. To set the audit level for a DCL file, include a line such as the following anywhere within the DCL file, but not inside any tile definitions:

dcl_settings : default_dcl_settings { audit_level = 3; }

If your DCL file references other DCL files with include directives, you should define dcl_settings in only one file. The defined audit level is used in all included files. The following table describes each audit level:

Semantic auditing levels
Level | Description
0 | No checking. Use only if the DCL files have been audited and have not been touched since the audit.
1 | Errors. Finds DCL bugs that may cause AutoCAD to terminate. This level of checking is the default and involves almost no delay. Errors can include using undefined tiles and circular prototype definitions.
2 | Warnings. Finds DCL bugs that result in dialog boxes with undesired layout or behavior. A modified DCL file should be audited at this level at least once. The warning level catches mistakes such as missing required attributes and inappropriate attribute values.
3 | Hints. Finds redundant attribute definitions.

To get the most out of the auditing facility, you should keep the audit_level at 3 during program development. Remember to strip out the dcl_settings line before shipping DCL files to users.


Adjusting the Layout of Dialog Boxes

Semantic Auditing of DCL Files
Designing Dialog Boxes
Distributing Tiles in a Cluster
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes >
Adjusting the Layout of Dialog Boxes

Look again at the sample dialog box defined in the previous section. There is a small problem with it:

Notice how the OK button occupies almost the full width of the dialog box. To improve the appearance of this dialog box, you can edit the DCL file and add two attributes to the button tile. To prevent the button from filling the available space, add a fixed_width attribute and set it to true. This causes the button's border to shrink so that it is just slightly wider than the text inside. To center the button, add an alignment attribute that specifies centered. Tiles in a column are left-justified by default. Now the DCL description is as follows:

hello : dialog {
    label = "Sample Dialog Box";
    : text {
      label = "Hello, world";
    }
    : button {
      key = "accept";
      label = "OK";
      is_default = true;
      fixed_width = true;
      alignment = centered;
  }
}

The dialog box now appears like the following:

Many common layout problems can be resolved with the techniques that are described in the following subsections. If the default layout is not suitable to the dialog box you are creating, adjust the layout by changing the defaults at the prototype or subassembly level. Adjust individual tiles only when necessary.

Topics in this section

  • Distributing Tiles in a Cluster
  • Adjusting the Space between Tiles
  • Adjusting Space at the Right Side or Bottom
  • Fixing the Spacing Around a Boxed Row or Column
  • Customizing Exit Button Text


Distributing Tiles in a Cluster

Adjusting the Layout of Dialog Boxes
Adjusting the Layout of Dialog Boxes
Adjusting the Space between Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Adjusting the Layout of Dialog Boxes >
Distributing Tiles in a Cluster

When laying out tiles in a dialog box, you need to arrange them into rows and columns based on the relative size of each tile. The following DCL defines a row of three tiles that runs along the top of another tile:

: column {
          : row {
            : compact_tile {
            }
            : compact_tile {
            }
            : compact_tile {
            }
          }
          : large_tile {
          }
}

If the compact_tile components have fixed_width and the large_tile is wider than the minimum space required by the row of compact_tiles above it, the default horizontal alignment of this assembly appears as follows:

The leading edge of the first compact_tile in the row aligns with the leading edge of the large_tile, and the trailing edge of the last compact_tile aligns with the trailing edge of the large_tile. Tiles in between are distributed evenly. The situation with adjoining columns is analogous.

You can control the default distribution by using the spacer_0 and spacer_1 tiles, which are variants of the spacer tile defined in base.dcl. See DCL Attribute Catalog for more information on these tiles.


Adjusting the Space between Tiles

Distributing Tiles in a Cluster
Adjusting the Layout of Dialog Boxes
Adjusting Space at the Right Side or Bottom
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Adjusting the Layout of Dialog Boxes >
Adjusting the Space between Tiles

If two adjoining columns differ greatly in the amount of space their tiles occupy, then the tiles in the one that needs less space may appear to be distributed too far apart. Their appearance can be improved if you set the incongruous column's fixed_height attribute to true. The result for vertical tile distribution is shown in the following diagram:


Adjusting Space at the Right Side or Bottom

Adjusting the Space between Tiles
Adjusting the Layout of Dialog Boxes
Fixing the Spacing Around a Boxed Row or Column
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Adjusting the Layout of Dialog Boxes >
Adjusting Space at the Right Side or Bottom

A dialog box may contain unused space along its right side. You can define a text tile and explicitly specify a width greater than the width required by its current value. For example, the following code fragment defines a tile that does not display anything (its value is null) until an application sets its value:

: text {
          key = "l_text";
          width = 18;
          fixed_width = true;
}

The width attribute reserves space for 18 characters in the dialog box. The application can add text with a statement like the following:

(set_tile "l_text" "By layer")

Because "By layer" doesn't need all 18 characters, the dialog box has surplus space along its right side.

A similar situation occurs when you use an errtile to display error messages. (See Dialog Box Exit Buttons and Error Tiles.) Unless an error message is currently shown, it looks as if there is extra space at the bottom of the dialog box. In this case, an extra spacer tile at the top of the dialog box can help balance the vertical layout.


Fixing the Spacing Around a Boxed Row or Column

Adjusting Space at the Right Side or Bottom
Adjusting the Layout of Dialog Boxes
Customizing Exit Button Text
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Adjusting the Layout of Dialog Boxes >
Fixing the Spacing Around a Boxed Row or Column

If the label attribute of a boxed row or column is either blank ("") or null (""), the box encloses the cluster but no text is shown. A single blank does not appear as a space in the box. However, there is a difference in the way blank and null labels are laid out:

  • If the label is a single blank, any vertical space the text occupied inside the box is lost, but any vertical space the label occupied above the box is not lost.
  • If the label is a null string, all vertical space is lost, whether above the box or inside it.

In the following DCL code, the top lines of the boxes around the first two columns are guaranteed to line up (with the same Y location), and the top line of the box around the third column is guaranteed to have no spacing above or below it, except for the default margins:

: row {
        : boxed_column {
           label = "Some Text";
        }
        : boxed_column {
           label = " ";         // single blank: the default
        }
        : boxed_column {
           label = "";         // null string
        }
}


Customizing Exit Button Text

Fixing the Spacing Around a Boxed Row or Column
Adjusting the Layout of Dialog Boxes
Design Guidelines
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Adjusting the Layout of Dialog Boxes >
Customizing Exit Button Text

For some dialog boxes, you may want to change the text of one of the exit buttons. For example, if you create a dialog box capable of destroying data, it's safer to call the button Destroy instead of OK. To do this, use the retirement_button prototype as follows:

destroy_button : retirement_button {
               label = "&Destroy";
               key = "destroy";
}

Notice the use of the ampersand (&) in the label attribute. This assigns a mnemonic to the tile. In this case the letter D is underscored in the button label and becomes the mnemonic.

NoteWhen customizing existing button subassemblies, you should obtain the proper DCL code from your base.dcl file rather than from the manual.

Once you have defined a custom exit button, you need to embed it in a subassembly that matches the appearance and functionality of the standard clusters. The following example shows the current definition of ok_cancel_help:

ok_cancel_help : column {
             : row {
                fixed_width = true;
                alignment = centered;
                ok_button;
                : spacer { width = 2; }
                cancel_button;
                : spacer { width = 2; }
                help_button;
              }
}

Create a new subassembly that replaces the ok_button with the new button as follows:

destroy_cancel_help : column {
              : row {
                 fixed_width = true;
                 alignment = centered;
                 destroy_button;
                 : spacer { width = 2; }
                 cancel_button;
                 : spacer { width = 2; }
                 help_button;
              }
}

In the standard subassembly, the OK button is the default, but this attribute wasn't added to destroy_button. Where the dialog box's action can be destructive (or very time-consuming), it is strongly recommended to make the Cancel button the default. In this case, it functions both as the default and as the Abort button:

destroy_cancel_help : column {
              : row {
                 fixed_width = true;
                 alignment = centered;
                 destroy_button;
                 : spacer { width = 2; }
                 : cancel_button { is_default = true; }
                 : spacer { width = 2; }
                 help_button;
              }
}

Because an attribute has been changed, the original Cancel button is used as a prototype, requiring a colon in front of cancel_button.

WarningWhen the Cancel button and the Default button are the same (both is_default and is_cancel are true) and you neglect to assign an action that calls done_dialog to any other button, then no other button can exit the dialog box and it will always be canceled.


Design Guidelines

Customizing Exit Button Text
Designing Dialog Boxes
Aesthetics and Ergonomics
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes >
Design Guidelines

To design a dialog box well, you must consider not only the practical purpose of the box but also its aesthetics, the ergonomics of using it, and the GUI standards for the Windows environment. The following subsections provide some guidelines for GUI design, dialog box design, and predefined tiles and clusters. Refer to Programmable Dialog Box Function Synopsis for more examples of tiles and clusters.

Topics in this section

  • Aesthetics and Ergonomics
  • Consistent Design and Clear Language
  • User Control
  • Forgiving Errors
  • Providing Help
  • Users with Disabilities
  • Using Capitalization
  • Avoiding Abbreviations
  • Layout
  • Size and Placement
  • Disabling Tiles
  • Nesting Dialog Boxes
  • Closing a Dialog Box for User Selection
  • Providing Defaults
  • Handling Keyboard Input
  • International Language Considerations
  • Guidelines for Predefined Tiles and Clusters
  • Error Handling in Dialog Boxes


Aesthetics and Ergonomics

Design Guidelines
Design Guidelines
Consistent Design and Clear Language
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Aesthetics and Ergonomics

The appearance of a dialog box is important. If the box is too cluttered, it is ineffective and hard to use. Also, tiles should be arranged so they are easy to use. Consider which tiles will be used most frequently, make them prominent in the design, and arrange them so it's easy to move between them, particularly when they are used in conjunction with each other.


Consistent Design and Clear Language

Aesthetics and Ergonomics
Design Guidelines
User Control
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Consistent Design and Clear Language

The user interface of an application should be internally consistent, and consistent with related applications. An unfamiliar dialog box is easier to understand if its design is consistent with other dialog boxes in the application, related applications, or the host system. One example of this is the consistent placement of buttons such as OK and Cancel. The technique associated with each kind of tile—how you enter text in a text box and how you select a list box item—should also be consistent. The best way to achieve consistency is to reuse tiles and the code that controls them.

Standardization contributes to consistency. Use standard definitions for dialog box controls. This reduces your work, contributes to consistency, and makes it easier for users to learn and use your dialog boxes.

Use language that is clear. Although dialog boxes are considered part of a graphical interface, most of the tiles and information they present are textual. The labeling of dialog boxes, naming of buttons, and phrasing of messages should be direct and unambiguous. Avoid jargon and technical terms that users may not understand.


User Control

Consistent Design and Clear Language
Design Guidelines
Forgiving Errors
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
User Control

Give users some control over how they access the dialog box to enter input. One advantage of using dialog boxes instead of a command line interface is that boxes don't confine users to a strict sequence of prompts. In a dialog box, users should be able to enter input in any sequence. Some constraints are necessary—when selecting one option causes another to be unavailable, for example—but build in only constraints that have underlying reasons in the way your application works.

For example, the following figure shows the Object Grouping dialog box. This dialog box contains a Group Name field, where users may enter a name for a new group they are creating. If the Unnamed option is selected, a Group Name cannot be specified.

Multiple dialog boxes should appear on top of one another rather than require the user to exit the current box before calling another. Always let users return to the dialog box that was initially displayed. This design doesn't commit users to a choice before they are ready to leave the dialog box. Because the current dialog box appears on top of the previous one, it reminds users of the context: where they have come from and where they'll return to.

Whenever users do something to change the current status or options, provide them with immediate feedback. If users select something, show it or describe it immediately. If one choice excludes other choices, be sure to make the invalid choices unavailable immediately.

In the AutoCAD Color Selection dialog box, for example, an image tile shows the color immediately after the user selects its number. In the sample Block Definition dialog box, the number of selected objects is always displayed in a message below the Select Objects button:


Forgiving Errors

User Control
Design Guidelines
Providing Help
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Forgiving Errors

Make your dialog boxes forgiving, so users feel free to explore without fear of making irreversible mistakes. Report minor errors by messages in an error tile at the bottom of the dialog box. Report more serious errors by displaying an alert box. The alert function displays a simple alert box (with a single OK button). See in the AutoLISP Reference.

If the user selects a potentially destructive or time-consuming action, the dialog box should display an alert box that gives the user a choice of proceeding with the operation or canceling it.

For example, in the Block Definition dialog box, an alert box appears when users attempt to create a block that already exists. Users can then choose to proceed and overwrite the original block, or cancel the operation without making changes:

Nested dialog boxes that alert users should return to the previous dialog box. Terminate the current nest of dialog boxes only in the case of serious or potentially fatal errors.


Providing Help

Forgiving Errors
Design Guidelines
Users with Disabilities
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Providing Help

You should provide a Help facility. How much Help you provide depends on how complex your application is and how self-explanatory your dialog boxes are. At the very least, it is recommended that the main dialog box of your application have a Help button that displays a single dialog box describing important information. In most cases, the Help button should call the Help facility using the help function.

If your application is more sophisticated, consider using a Help button in each dialog box.


Users with Disabilities

Providing Help
Design Guidelines
Using Capitalization
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Users with Disabilities

Considerations intended for users with disabilities can make a program easier for anyone to use. When designing your dialog boxes, consider the following:

Color

Many people cannot distinguish between certain colors. If you use color coding to present information, supplement this by presenting the same information in some other way (usually with text).

For example, the standard AutoCAD Color dialog box displays a text message that states the color's name or number as well as an image tile that displays the color.

Online Help

Many users have difficulty either reading the small print in manuals or physically handling books. Even a single Help button on the main dialog box can be useful.

Keyboard Access

Some users may have difficulty with or be unable to use a pointing device. Try to specify mnemonics so your dialog boxes can be used with just the keyboard.

Clarity and Simplicity

Carefully designed dialog boxes with clear and simple language help users with verbal or cognitive impairments. Don't force users to remember many different things. Instead, use consistent terminology and present choices wherever possible.


Using Capitalization

Users with Disabilities
Design Guidelines
Avoiding Abbreviations
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Using Capitalization

The following are some general guidelines for capitalizing text within dialog boxes:

Dialog Boxes, Areas, and Column Headings

Use headline capitalization: capitalize the first and last words, and all other words except articles, prepositions, and coordinating conjunctions. However, if the dialog box is invoked from a menu (not from the Command prompt), its title should match the menu item.

Control Labels

Use headline capitalization for labels of control tiles such as buttons. Do not follow labels with a period. Follow the labels of a text box or a drop-down list with a colon (:). You may want to use sentence-style capitalization (in which you capitalize only the first word and proper nouns) if the label is lengthy or phrased as a question.

Prompts and Messages

Use sentence-style capitalization.


Avoiding Abbreviations

Using Capitalization
Design Guidelines
Layout
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Avoiding Abbreviations

Abbreviations can be ambiguous and difficult to translate. If space constraints require you to abbreviate terms, abbreviate them consistently within a group (such as a boxed column). Be consistent. Don't spell some terms in full and abbreviate others.


Layout

Avoiding Abbreviations
Design Guidelines
Size and Placement
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Layout

Arrange sections of the dialog box logically into rows or columns so users can scan them from left to right or from top to bottom. Align related entry fields (such as edit boxes or list boxes) both vertically and horizontally, so that when users switch fields by pressing TAB, the cursor moves in a straight, orthogonal line.

If there is a natural order for entering data—such as the X, Y, and Z of coordinates—order the fields in the same way. Align boxed areas both vertically and horizontally. Do not leave a lot of white space around or between boxed areas. Extend their width to the right, if necessary.


Size and Placement

Layout
Design Guidelines
Disabling Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Size and Placement

To display information clearly, make the dialog box no larger than necessary.

NoteUsers may have a screen resolution as low as 640×480. If you are developing applications on displays using a higher resolution, remember to verify that your dialog boxes display properly at lower resolutions.

By default, AutoCAD initially displays all dialog boxes in the center of the graphics window. However, you can specify that dialog boxes display at an alternate location (such as the last location specified by the user). The new_dialog and done_dialog AutoLISP functions provide for dialog box placement.


Disabling Tiles

Size and Placement
Design Guidelines
Nesting Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Disabling Tiles

If a tile or an area is unavailable or irrelevant given the current option settings, disable it immediately so the tile or area is unavailable and the user can't select it. Try not to overuse the disabling tiles feature. Too many unavailable tiles can be distracting.

If a tile displays a value, disabling the tile shouldn't affect the value. The tile should display the same value when it is enabled again. Values that change magically create more work for the user, which is annoying and distracting.


Nesting Dialog Boxes

Disabling Tiles
Design Guidelines
Closing a Dialog Box for User Selection
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Nesting Dialog Boxes

AutoCAD limits the number of nested dialog boxes to eight. For information on how to handle nested dialog boxes, see Nesting Dialog Boxes.

Insert an ellipsis (…) in the label of a button that displays a nested dialog box unless the nested dialog box is an alert box. Don't nest dialog boxes more than three deep. Four levels of nesting are reasonable if the fourth-level dialog boxes are only alert boxes. Because dialog boxes appear initially in the center of the screen, make the nested dialog boxes smaller than the main dialog box.


Closing a Dialog Box for User Selection

Nesting Dialog Boxes
Design Guidelines
Providing Defaults
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Closing a Dialog Box for User Selection

If a user needs to make a selection from the graphics screen before the dialog box has closed, you must close the dialog box momentarily so that the user can see the screen and make the selection. This is known as hiding a dialog box. Once the selection is made, you need to display the dialog box again.

The label of a button that causes the dialog box to be hidden should not contain an ellipsis. Instead, use a space followed by a less-than symbol (<) in the label. When the dialog box hides itself, a prompt should be displayed that explains what the user is expected to do.

In most cases, you can get the input with one of the getxxx functions. These functions have an argument with which you can specify a prompt.

When the dialog box reappears, it should contain feedback on the selection process. This can be new information in the edit box fields, an updated list box, a text message that indicates the status, or a combination of these.


Providing Defaults

Closing a Dialog Box for User Selection
Design Guidelines
Handling Keyboard Input
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Providing Defaults

Provide reasonable defaults for all entries and options. Well-chosen defaults can help users complete a dialog box quickly and easily.

It is recommended that you update the default values—in other words, that you save the user's previous settings and use them as the new defaults—each time the dialog box is used. Even if the user has to change some of these, it is less work than starting from the beginning each time.


Handling Keyboard Input

Providing Defaults
Design Guidelines
International Language Considerations
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Handling Keyboard Input

When you create a custom dialog box, you can specify how it handles keyboard shortcuts. Some keyboard shortcuts are common to all dialog boxes. For example, the TAB key generally enables users to move from tile to tile, and the SPACEBAR allows users to turn toggles off or on. Each active tile should be a tab stop (the default).

Two keys commonly act as accelerator keys. The accept key (usually the ENTER key) accepts the dialog box and values entered. The cancel key (ESC), discards the dialog box and the values. When AutoCAD first displays a dialog box, one of its tiles has the initial keyboard focus. What the user enters affects this tile until the user moves focus to another tile.

To move from tile to tile, the user can press TAB, choose another tile, or enter one of the keyboard shortcuts known as mnemonic keystrokes. Moving between tiles changes focus but doesn't make a selection. To select a tile that has focus, users must press ENTER. For some kinds of tiles, a double-click is equivalent to pressing ENTER.


International Language Considerations

Handling Keyboard Input
Design Guidelines
Guidelines for Predefined Tiles and Clusters
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
International Language Considerations

Words in other languages often require more characters than their English equivalents. If your dialog boxes are going to be translated, leave as much room as possible for them to grow. The following table shows some familiar AutoCAD terms with their equivalents in French and German.

Equivalent AutoCAD terms in English, French, and German
English | French | German
Line | Ligne | Linie
Arc | Arc | Bogen
Circle | Cercle | Kreis
3D Polylines | Polylignes 3D | 3D-Polylinien
Diameter dimensioning | Cotation de diamtre | Durchmesserbemaung
Layers | Calque | Layer
Linetypes | Types de ligne | Linientypen
Entity creation modes | Modes de cration des objets | Modus fr Objekterzeugung
Select objects | Choix des objets | Objekte whlen
OK | OK | OK
Cancel | Annuler | Abbruch
Help | Aide | Hilfe


Guidelines for Predefined Tiles and Clusters

International Language Considerations
Design Guidelines
Buttons
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Guidelines for Predefined Tiles and Clusters

This section lists recommended conventions and design guidelines associated with particular kinds of predefined tiles and tile clusters.

Topics in this section

  • Buttons
  • Clusters
  • Edit Boxes
  • Image Buttons and Image Tiles
  • List Boxes
  • Radio Buttons, Radio Rows, and Radio Columns
  • Sliders
  • Text
  • Toggles


Buttons

Guidelines for Predefined Tiles and Clusters
Guidelines for Predefined Tiles and Clusters
Clusters
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Buttons

The action associated with a button should be visible to the user and should take place immediately. The label of a button should be unambiguous. Usually, it should be a verb that describes the effect of pushing the button, though another label—such as OK or Options—is acceptable if its meaning is clear. For buttons that call other dialog boxes or hide the current dialog box, see Nesting Dialog Boxes and Closing a Dialog Box for User Selection.

Buttons in a column should be the same width. In other cases, buttons should have a fixed width (either fixed_width = true;, or children_fixed_width = true;) in their common parent cluster.


Clusters

Buttons
Guidelines for Predefined Tiles and Clusters
Edit Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Clusters

A boxed cluster (a row or column) is called a group box or an area. An area provides a visual cue to users by isolating and naming controls that work together. The area can contain as many tiles, rows, and columns (unboxed) as necessary. The label of an area should indicate its purpose.

If controls relate to each other, put them in an area. The Base Point cluster in the Block Definition sample dialog box demonstrates this technique with an area formed from a cluster with a label and a border:

However, do not overuse areas. White space is also an effective way to group tiles. Do not put a box around a list box; this looks too busy.


Edit Boxes

Clusters
Guidelines for Predefined Tiles and Clusters
Image Buttons and Image Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Edit Boxes

The length of the text-entry portion of an edit box should roughly equal the length of an average entry. When in doubt, use a character width of 10 for real number fields and 20 for text fields.

The label of an edit box should end with a colon (:).

If there are restrictions on what users can enter in the edit box, put a text tile to the right of the edit box that briefly explains these restrictions. If users need to enter a file name, for example, there's no need to explain what a file name is. But if the string is a number that cannot exceed 100, a reminder of this limit is a good idea.

For data, such as points, provide two or three edit boxes rather than require users to remember the Command line syntax of point entry. One exception is an edit box intended specifically for entering advanced syntax, such as the wild-card pattern edit box in the AutoCAD File Search dialog box.


Image Buttons and Image Tiles

Edit Boxes
Guidelines for Predefined Tiles and Clusters
List Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Image Buttons and Image Tiles

If you use an image button or image tile as an icon to alert the user—for example, a warning signal such as a stop sign—use it consistently in all dialog boxes.

When you use image buttons to represent selections, supplement the image with text that briefly describes it, especially if the color of the image (or part of the image) is a factor in selecting it.


List Boxes

Image Buttons and Image Tiles
Guidelines for Predefined Tiles and Clusters
Radio Buttons, Radio Rows, and Radio Columns
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
List Boxes

Because DCL list boxes cannot be scrolled horizontally, the width of the list box should accommodate the longest item in the list. Provide a label (or a text tile) to explain the contents of the list box, unless the list box is the main tile in the dialog box. In that case the dialog box's label might be sufficient—although you must give the list box a label if you want users to be able to move to that list box by using a mnemonic.

Alphabetize the items in the list unless you have a logical reason to organize them in some other way. If the length of the list is fixed and short, consider using a radio column instead of a list box.


Radio Buttons, Radio Rows, and Radio Columns

List Boxes
Guidelines for Predefined Tiles and Clusters
Sliders
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Radio Buttons, Radio Rows, and Radio Columns

Radio columns look better and are easier to use than radio rows.

Radio rows are appropriate only when they contain a small number of buttons (usually, two to four) or if the labels are short. If an option selected elsewhere makes the choices in the radio row or radio column invalid or irrelevant, then disable the whole row or column. In some situations, an option selected elsewhere may make certain radio buttons invalid or irrelevant. In situations like this, you can disable buttons individually.


Sliders

Radio Buttons, Radio Rows, and Radio Columns
Guidelines for Predefined Tiles and Clusters
Text
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Sliders

The granularity of a slider should not be too coarse. For example, if a slider is assigned only four incremental values but is laid out in a two-inch section of the dialog box, users would have to move half an inch to see a change. Avoid jumpiness like this by scaling the size of the slider.

If users need to know the value controlled by the slider, your dialog box should also display the slider's current value. Update this value whenever the slider is moved. It is recommended you also display an edit box that enables users to enter the value rather than use the slider. If you use an edit box this way, update its value; otherwise, display the value in a text tile. The following figure shows a typical combination of slider and edit box:


Text

Sliders
Guidelines for Predefined Tiles and Clusters
Toggles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Text

When labels are not sufficient, use text tiles to identify the purpose of individual tiles or dialog box areas. You can also use text tiles to display status messages or reminders, including error messages and warnings.

Text should be direct and unambiguous. Describe options and entry fields in terms your users would use. For example, the error message “Invalid entry” in a list box conveys little information. A message such as “Layer does not exist” is more helpful.

Align messages with the control tiles they describe.

Put text that identifies a group of control tiles or a section of the dialog box above the tiles that the text describes.


Toggles

Text
Guidelines for Predefined Tiles and Clusters
Error Handling in Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Guidelines for Predefined Tiles and Clusters >
Toggles

When the options controlled by toggles relate to the same topic, group them together.

Use a single toggle that controls whether other tiles, often in a row or column, are active. In this case, the toggle should be prominent. When the toggle controls only one other tile, you can also place it to the right of that tile. The toggle in the following dialog box enables or disables another tile:


Error Handling in Dialog Boxes

Toggles
Design Guidelines
Error Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines >
Error Handling in Dialog Boxes

Dialog boxes can display error messages and warnings with a text tile known as an error tile (errtile), or with a nested alert box. The following guidelines apply to both:

  • Error messages should be complete sentences, punctuated as such, with an initial capital and a period at the end.
  • Error messages should explain clearly the problem or potential problem.
  • After reporting the error, shift the dialog box's focus to the tile that triggered the error, if possible.

Topics in this section

  • Error Tiles
  • Alert Boxes


Error Tiles

Error Handling in Dialog Boxes
Error Handling in Dialog Boxes
Alert Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Error Handling in Dialog Boxes >
Error Tiles

Use an error tile for minor errors or warnings, especially those that arise from typographical errors.

Do not display errors in text tiles used for status messages. These are easy to overlook.

Error tiles should appear at the bottom of a dialog box. Use the standard errtile described in Dialog Box Exit Buttons and Error Tiles.


Alert Boxes

Error Tiles
Error Handling in Dialog Boxes
Managing Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Designing Dialog Boxes > Design Guidelines > Error Handling in Dialog Boxes >
Alert Boxes

You can display a standard alert box with a single OK button by calling the alert function. Use alert boxes for serious or potentially fatal errors, but do not overuse them. Alert boxes require user input. Therefore, they can be annoying, especially when they report minor errors or obscure the entry that needs to be corrected.

Use alert boxes to warn users that the action about to begin can destroy data or can be time consuming. Alert boxes of this sort should give users a choice of proceeding or canceling the action. If the alert box offers users a choice, such as Proceed or Cancel, you must construct it yourself.

If the alert box provides users with a choice, the text in the alert box should first describe the problem and then pose the next action as a question. In such cases it is important that the button for proceeding be labeled with a verb that describes what will happen. In this context, Overwrite, for example, is less ambiguous than OK, and is an aid to experienced users who will gloss over the text because they have seen this alert box many times.

Unless the error is truly fatal, provide a way for users to return to a previous step or escape from the operation that triggered the alert box.

Usually the default button for a dialog box is OK or its equivalent, but when the situation described by the alert box has serious consequences, make Cancel or its equivalent the default.


Managing Dialog Boxes

Alert Boxes
Working with Programmable Dialog Boxes
Controlling Dialog Boxes with AutoLISP Programs
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes >
Managing Dialog Boxes

You can use dialog boxes to respond to user input.

With AutoCAD®, you can design and implement dialog boxes to use with your applications. The appearance of a dialog box is defined by dialog control language (DCL) files, as described in Designing Dialog Boxes. You control the functionality of a dialog box with an AutoLISP® application. This chapter describes how to control dialog boxes using AutoLISP. Although this chapter shows some examples of DCL files, you may find it helpful to read Designing Dialog Boxes before reading this chapter.

Topics in this section

  • Controlling Dialog Boxes with AutoLISP Programs
  • Action Expressions and Callbacks
  • Handling Tiles
  • Nesting Dialog Boxes
  • Functions for Hiding Dialog Boxes
  • List Boxes and Pop-Up Lists
  • Image Tiles and Buttons
  • Application-Specific Data
  • DCL Error Handling
  • Dialog Box Function Summary


Controlling Dialog Boxes with AutoLISP Programs

Managing Dialog Boxes
Managing Dialog Boxes
Quick Overview
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Controlling Dialog Boxes with AutoLISP Programs

This chapter begins with an overview of the process you use to display dialog boxes and respond to user input from an AutoLISP program.

Topics in this section

  • Quick Overview
  • Functions Restricted When a Dialog Box Is Open


Quick Overview

Controlling Dialog Boxes with AutoLISP Programs
Controlling Dialog Boxes with AutoLISP Programs
Functions Restricted When a Dialog Box Is Open
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Controlling Dialog Boxes with AutoLISP Programs >
Quick Overview

This example starts with a simple dialog box:

The following DCL defines the dialog box:

hello : dialog {
    label = "Sample Dialog Box";
    : text { label = "Hello, world."; }
    ok_only;
}

This DCL defines a dialog box labeled Sample Dialog Box that contains a text tile and a single OK button. The DCL resides in a file named hello.dcl.

To display the dialog box and respond to the user pressing OK

  1. Use the load_dialog function to load the DCL file into memory. For example:
    (setq dcl_id (load_dialog "hello.dcl"))

    The load_dialog function returns a DCL identification number. You need this to identify the dialog in subsequent function calls.

  2. Call the new_dialog function and pass it the dialog name and DCL identification number as arguments, as follows:

    (new_dialog "hello" dcl_id)
  3. Initialize the dialog box by setting up tile values, lists, and images.

    The DCL example above uses a predefined tile named ok_only, so you do not have to initialize the tile unless you want to override its default values. The ok_only tile also has an action named done_dialog assigned to it. If the user presses the OK button, AutoCAD passes the done_dialog call to your AutoLISP application and ends the dialog.

  4. Call start_dialog to pass control of the dialog to AutoCAD for display to the user:
    (start_dialog)
  5. Call unload_dialog to remove the dialog from memory after the user responds.

    Steps 3, 4, and 5 are dependent on the new_dialog function returning a non-nil value. For the sake of simplicity, no error processing is included in this example.

You can use the following function to call the sample dialog box:

(defun C:HELLO( / dcl_id )
  (setq dcl_id (load_dialog "hello.dcl")) ; Load the DCL file.
  (if (not (new_dialog "hello" dcl_id))   ; Initialize the dialog.
    (exit)                                ; Exit if this doesn't
                                          ; work.
  )
  (start_dialog)                          ; Display the dialog
                                          ; box.
  (unload_dialog dcl_id)                  ; Unload the DCL file.
  (princ)
)

Enter this code into a new VLISP text editor window and load the program by choosing Tools [image] Load Text in Editor from the VLISP menu. To display the dialog box, enter (c:hello) at the VLISP Console prompt.

Note that the start_dialog call remains active until the user selects a tile (usually a button) whose associated action expression calls done_dialog. The done_dialog call can be issued explicitly by the tile. The done_dialog call is also issued by the selected tile if its is_cancel attribute is set to true.

WarningIn theory, the dialog box facility takes control of input at the time you call start_dialog, but in Windows it takes control when you call new_dialog. This has no effect on writing programs. However, if you invoke these functions interactively (at the AutoCAD Command prompt or a VLISP window), you must enter them as one statement. Enclose them within a progn or another function. If you don't, the interactive call to new_dialog can freeze the screen. Calling new_dialog and start_dialog interactively can be useful during debugging. (For an example of using these functions interactively, see DCL Error Handling.)


Functions Restricted When a Dialog Box Is Open

Quick Overview
Controlling Dialog Boxes with AutoLISP Programs
Action Expressions and Callbacks
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Controlling Dialog Boxes with AutoLISP Programs >
Functions Restricted When a Dialog Box Is Open

While a dialog box is active—that is, during the start_dialog call—you cannot call any function that requires user input on the AutoCAD command line, or affects the display outside the dialog box (for example, in the AutoCAD graphics window). This restriction includes functions that write text, such as print, princ, and prin1.

You can issue ssget calls, as long as you do not use any options that require user input.

If your program calls one of the restricted functions between the start_dialog and done_dialog calls, AutoCAD terminates all dialog boxes and displays the following error message:

AutoCAD rejected function

You can test the CMDACTIVE system variable to determine if a dialog box is active. If CMDACTIVE is greater than 7, a dialog box is active. The CMDACTIVE system variable has bit-coded values that indicate command, script, and dialog box activity.

NoteIf your application requires users to enter input based on the graphics screen rather than on the dialog box itself (for example, to specify a point or select an object), you must hide the dialog box. That is, you must call done_dialog so the graphics screen is visible again, and then restart the dialog box after the user has made the selection. For more information, see Functions for Hiding Dialog Boxes.

The term_dialog function terminates all current dialog boxes as if the user had canceled each of them. This function can be used to cancel a series of nested dialog boxes.


Action Expressions and Callbacks

Functions Restricted When a Dialog Box Is Open
Managing Dialog Boxes
Action Expressions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Action Expressions and Callbacks

To define the action taken when a certain tile in a dialog box is selected, you associate an AutoLISP expression with that tile by calling the action_tile function. This is known as an action expression. Within the action expression, you often need access to attributes in the DCL file. The get_tile and get_attr functions provide this capability. The get_attr function retrieves the user-defined attributes within the DCL file. The get_tile function gets the current runtime value of a tile based on user input to that tile. Action expressions must be defined following the new_dialog call and before the start_dialog call.

Information relating to how the user has selected a tile or modified a tile's contents is returned to the action expression as a callback. In most cases, every active tile within a dialog box can generate a callback. As with reactors, the action expression that responds to the callback is often referred to as a callback function. This function should perform validity checking on the associated tile and should update information in the dialog box that pertains to the value of the tile. Updating the dialog box can include issuing an error message, disabling other tiles, and displaying the appropriate text in an edit box or list box.

Only the OK button (or its equivalent) should query the tile values to permanently save the settings that the user has finally selected. In other words, you should update the variables associated with tile values within the callback for the OK button, not the callback for an individual tile. If permanent variables are updated within the individual tile callbacks, there is no way to reset the values if the user selects the Cancel button. If the OK button's callback detects an error, it should display an error message and return focus to the tile in error; it should not exit the dialog box.

When a dialog box includes several tiles whose handling is similar, it can be convenient to associate those tiles with a single callback function. The principle of not committing to the user's changes until the user chooses OK still applies.

There are two ways to define actions other than calling action_tile. You can define a default action for the entire dialog box when you call new_dialog, and you can define an action by using a tile's action attribute. These alternative means of defining actions, and the order in which they occur, are described in Default and DCL Actions.

Topics in this section

  • Action Expressions
  • Callback Reasons


Action Expressions

Action Expressions and Callbacks
Action Expressions and Callbacks
Callback Reasons
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Action Expressions and Callbacks >
Action Expressions

An action expression can access the variables shown in the following table, indicate which tile was selected, and describe the tile's state at the time of the action. The variable names are reserved. Their values are read-only and have no meaning, unless they are accessed within an action expression.

Action expression variables

Variable

Description

$key

The key attribute of the tile that was selected.

This variable applies to all actions.

$value

The string form of the current value of the tile, such as the string from an edit box, or a "1" or "0" from a toggle.

This variable applies to all actions.

If the tile is a list box (or pop-up list) and no item is selected, the $value variable will be nil.

$data

The application-managed data (if any) that was set just after new_dialog time by means of client_data_tile.

This variable applies to all actions, but $data has no meaning unless your application has already initialized it by calling client_data_tile. See Application-Specific Data.

$reason

The reason code that indicates which user action triggered the action. Used with edit_box, list_box, image_button, and slider tiles.

This variable indicates why the action occurred. Its value is set for any kind of action, but you need to inspect it only when the action is associated with an edit_box, list_box, image_button, or slider tile. See Callback Reasons in the following section for details.

If edit1 is a text box, the action expression in the following action_tile call is evaluated when the user exits the text box:

(action_tile "edit1" "(setq ns $value)")

The $value contains the string that the user entered, and the expression saves this in the ns variable.

The next example saves the name of the selected tile so that the program can refer to it:

(action_tile "edit1" "(setq newtile $key)")

The newtile variable is set to the key name of the selected tile, in this case "edit1". The $key variable is very useful within a function that serves as the action for several separate tiles.

When a tile is named in more than one action_tile call, only the last such call (prior to start_dialog) has any effect. (It's as if you were to assign multiple values to the same variable.) The programmable dialog box (PDB) feature allows only one action per tile.


Callback Reasons

Action Expressions
Action Expressions and Callbacks
Default and DCL Actions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Action Expressions and Callbacks >
Callback Reasons

The callback reason, returned in the $reason variable, specifies why the action occurred. Its value is set for any kind of action, but you need to inspect it only when the action is associated with an edit_box, list_box, image_button, or slider tile. The following table shows the possible values:

Callback reason codes
Code | Description
1 | This is the value for most action tiles. The user has selected the tile (possibly by pressing ENTER, if the tile is the default and the platform recognizes accelerator keys).
2 | Edit boxes: The user has exited the edit box, but has not made a final selection.
3 | Sliders: The user has changed the value of the slider by dragging the indicator but has not made a final selection.
4 | List boxes and image buttons: This callback reason always follows a code 1. It usually means “commit to the previous selection.” It should never undo the previous selection; this confuses and annoys the user.

Code 1 is described fully in the table. The following text describes the codes 2, 3, and 4 in greater detail.

Code 2—Edit Boxes

The user has exited the edit box—by pressing the TAB key or by choosing a different tile—but has not made a final selection. If this is the reason for an edit box callback, your application should not update the value of the associated variable, but should check the validity of the value in the edit box.

Code 3—Sliders

The user has changed the value of the slider by dragging the indicator (or an equivalent action), but has not made a final selection. If this is the reason for a slider callback, your application should not update the value of the associated variable but should update the text that displays the slider's status. For more information, see Sliders. For code examples, see Handling Sliders.

Code 4—List Boxes

The user has double-clicked on the list box. You can define the meaning of a double-click in your application. If the main purpose of the dialog box is to select a list item, a double-click should make a selection and then exit the dialog box. (In this case, the is_default attribute of the list_box tile should be true.) If the list box is not the primary tile in the dialog box, then a double-click should be treated as equivalent to making a selection (code 1).

List boxes that allow the user to select multiple items (multiple_select = true) cannot support double-clicking.

Code 4—Image Buttons

The user has double-clicked on the image button. You can define the meaning of a double-click in your application. In many cases it is appropriate for a single-click to select the button, but in others it is better for a single-click (or a keyboard action) to highlight the button, and then have the ENTER key or a double-click select it.

Topics in this section

  • Default and DCL Actions


Default and DCL Actions

Callback Reasons
Callback Reasons
Handling Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Action Expressions and Callbacks > Callback Reasons >
Default and DCL Actions

The action_tile function is not the only way to specify an action. A tile's DCL description can include an action attribute in AutoLISP, and the new_dialog call can specify a default action for the dialog box as a whole. A tile can have only a single action at a time. If the DCL and the application specify more than one action, they supersede each other in the following order of priority (lowest to highest):

  • The default action specified by the new_dialog call (used only if no action is explicitly assigned to the tile).
  • The action specified by the action attribute in the DCL file.
  • The action assigned by the action_tile call (highest priority).


Handling Tiles

Default and DCL Actions
Managing Dialog Boxes
Initializing Modes and Values
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Handling Tiles

Your program has some control over the tiles that are in the current dialog box at initialization time and action (callback) time. This section introduces the tile-handling functions and shows how to initialize and modify the tiles' modes and values.

Topics in this section

  • Initializing Modes and Values
  • Changing Modes and Values at Callback Time
  • Handling Radio Clusters
  • Handling Sliders
  • Handling Edit Boxes


Initializing Modes and Values

Handling Tiles
Handling Tiles
Changing Modes and Values at Callback Time
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Handling Tiles >
Initializing Modes and Values

Initializing a tile can include the following:

  • Making it the initial keyboard focus of the dialog box
  • Disabling or enabling it
  • Highlighting its contents, if it is an edit box or image

These operations are performed by mode_tile calls. You can set the value of a tile by using set_tile.

To display a default value—such as a surname—in an edit box and set the dialog box's initial focus to that box, use the following code:

(setq name_str "Kenobi")         ; Default.
(set_tile "lastname" name_str)   ; Initializes field.
(mode_tile "lastname" 2)         ; 2 sets focus to tile.

An additional mode_tile call can highlight all the contents of an edit box, so the user has the option to type immediately over the default contents, as shown in the following example:

(mode_tile "lastname" 3)         ; 3 selects box contents.


Changing Modes and Values at Callback Time

Initializing Modes and Values
Handling Tiles
Handling Radio Clusters
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Handling Tiles >
Changing Modes and Values at Callback Time

At callback time, you can check the value of a tile. If necessary, you can use set_tile again to modify this value. During callbacks, you can also use mode_tile to change the status of a tile. The following table shows the values of the mode_tilemode argument:

Mode codes for mode_tile
Value | Description
0 | Enable tile
1 | Disable tile
2 | Set focus to tile
3 | Select edit box contents
4 | Flip image highlighting on or off

When you use mode_tile to disable a tile that has the current focus, you must call mode_tile again to set the focus to a different tile (in most cases, the next tab stop in the dialog box). Otherwise, the focus will remain on a disabled tile, which is illogical and can cause errors.

A good example of a tile disabling itself is a series of dialog box pages that the user steps through by choosing a Next or Previous button. When the user chooses Next on the next-to-last page, the button is disabled. The same thing happens after choosing Previous on the second page. In both cases, the code must disable the button that was chosen, and then set focus to a different tile.

Suppose the tile called group_on is a toggle that controls a cluster called group. When the toggle is turned off, the tiles in the cluster are inactive and should not be modified. In this case, you might define the following action for the toggle. (Notice the use of the \" control character, which allows quotation marks within an action_tile argument.)

(action_tile "group_on" "(mode_tile \"group\" (- 1 (atoi $value)))")

The subtraction and atoi call in the action expression set the mode_tile function's mode argument. Because a toggle is 0 when it is turned off and 1 when it is turned on, the subtraction inverts its value and the mode controls whether the cluster is enabled.

You can inspect attributes other than a tile's value with the get_attr function. For example, you may want to retrieve the label of a button called "pressme":

(get_attr "pressme" "label")

The get_attr function returns the value of the specified attribute as a string.

NoteIf you use get_attr to retrieve a value attribute, it gets the value attribute saved in the DCL file (the initial value of the tile). The get_tile function, however, gets the current runtime value of the tile. The two values are not necessarily the same.


Handling Radio Clusters

Changing Modes and Values at Callback Time
Handling Tiles
Handling Sliders
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Handling Tiles >
Handling Radio Clusters

Radio buttons appear in radio clusters. The value of each radio button is either "1" for On or "0" for Off. The value of the radio cluster is the key attribute of the currently selected button. The PDB feature manages the values of radio buttons in a cluster and ensures that only one button is turned on at a time. You can assign an action to each radio button, but it is more convenient to assign an action to the radio cluster as a whole and then test the cluster's value to see which radio button was chosen.

Consider the following example: A radio cluster controls the view of a three-dimensional object that is displayed after a user exits a dialog box. This cluster contains four radio buttons:

(action_tile "view_sel" "(pick_view $value)")
  .
  .
  .
(defun pick_view (which)
  (cond
    ((= which "front") (setq show_which 0))
    ((= which "top") (setq show_which 1))
    ((= which "left") (setq show_which 2))
    ((= which "right") (setq show_which 3))
  )
)

These examples show each radio button associated with a single variable that takes multiple values. These variables may also cause additional actions, such as disabling selections in your dialog box. If the radio cluster is large, you can store the associated values in a table. If you use a table, structure it so it doesn't depend on the order of the buttons within the cluster. The PDB feature does not impose this restriction, and the order can change if the DCL definition changes.


Handling Sliders

Handling Radio Clusters
Handling Tiles
Handling Edit Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Handling Tiles >
Handling Sliders

When you handle actions and callbacks from sliders, your application should check the reason code that it receives along with the callback. This is not required, but it is a good idea because it can reduce processing.

A callback occurs when an increment boundary on a slider is crossed. For example, if the slider is defined with a minimum value of 0, a maximum value of 10, and both small and big increments of 1, a callback is issued 10 times as the user traverses from one end of the slider to the other.

The following function shows the basic scheme of a function to handle a slider. It is called from an action expression associated with the slider tile. The slider_info tile used by the function displays the slider's current value in decimal form. Often such a tile is an edit box as well, which gives users the choice of either manipulating the slider or entering its value directly. If a user enters a value in slider_info, your edit box callback should update the value of the slider as follows:

(action_tile
  "myslider"
  "(slider_action $value $reason)"
)
(action_tile
  "slider_info"
  "(ebox_action $value $reason)"
)
  .
  .
  .
(defun slider_action(val why)
  (if (or (= why 2) (= why 1))    ; Check reason code.
  (set_tile "slider_info" val)    ; Show interim result.
  )
)
(defun ebox_action(val why)
  (if (or (= why 2) (= why 1))    ; Check reason code.
  ( set_tile "myslider" val)      ; Show interim result.
  )
)


Handling Edit Boxes

Handling Sliders
Handling Tiles
Nesting Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Handling Tiles >
Handling Edit Boxes

Actions and callbacks to handle edit boxes are similar to those for sliders. However, because characters in edit boxes are already visible, there is no need for action on interim results. Edit boxes only return a callback code when the focus to that tile is lost. The following code example checks the value but doesn't redisplay it:

(action_tile "myeditbox" "(edit_action $value $reason)")
  .
  .
  .
(defun edit_action (val why)
  (if (or (= why 2) (= why 4))
    . ; Do range checking on
    . ; transient value here.
    .
  )
)


Nesting Dialog Boxes

Handling Edit Boxes
Managing Dialog Boxes
Functions for Hiding Dialog Boxes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Nesting Dialog Boxes

You create and manage nested dialog boxes by calling new_dialog and start_dialog from within an action expression or callback function. For example, by including the following statement, a function can display the “Hello, world” box when the user chooses the button called button_1:

(action_tile "button_1" "(c:hello)")

The user must exit the nested dialog box before using the previous dialog box again.

AutoCAD imposes a limit of no more than eight nested dialog boxes, but to avoid confusion it is recommended you nest dialog boxes no deeper than four levels.

WarningIf you display nested dialog boxes by multiple new_dialog calls, be careful to balance each new_dialog call with a corresponding done_dialog call (whether called from a callback or not). Otherwise, your application may fail.

The term_dialog function terminates all current dialog boxes as if the user had canceled each of them. You can use this function if you need to cancel a series of nested dialog boxes.


Functions for Hiding Dialog Boxes

Nesting Dialog Boxes
Managing Dialog Boxes
Requesting a Password
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Functions for Hiding Dialog Boxes

A user cannot make an interactive selection while a dialog box is active. If you want the user to make a selection from the graphics screen, you must hide your dialog box and then restore it. Hiding the box is the same as ending it with done_dialog, except your callback function must use the done_dialog status argument to indicate that the dialog box is hidden—as opposed to ended or canceled. Set status to an application-defined value.

The start_dialog function returns the application-defined status when the dialog box disappears. Your program must then examine the status returned by start_dialog and determine what to do next. For standard and application-defined status values, see in the AutoLISP Reference.

For example, here is a simple dialog box that may require a user to pick a point in the AutoCAD graphics window:

The dialog box is defined with the following DCL:

hidedcl : dialog
{ label="Hide Example";
  : column
  { : text
    { key="message";
      label="Click PickMe to pick a point";
      fixed_width=true;
      fixed_height=true;
      alignment=centered;
    }
    :row
    { ok_only;
      :retirement_button
      { label    = "PickMe";
        key      = "hide";
        mnemonic = "H";
    }}}}

The function controlling the dialog box displays the window until the user presses OK or closes the window. If the user chooses PickMe, the code hides the dialog box and prompts the user to select a point. The following AutoLISP code controls the dialog box:

(defun c:hidedcl (/ dcl_id what_next cnt)
  (setq dcl_id (load_dialog "hidedcl.dcl"))  ;Load the dialog box.
  (setq what_next 2)
  (setq cnt 1)
  (while (>= what_next 2)                    ;Begin display loop.
    (if (null (new_dialog "hidedcl" dcl_id)) ;Initialize dialog
      (exit)                                 ;box, exit if nil
    ); endif                                 ;returned.
    ; Set action to take if a button is pressed. Either button
    ; results in a done_dialog call to close the dialog box.
    ; Each button associates a specific status code with
    ; done_dialog, and this status code is returned by
    ; start_dialog.
    (action_tile "accept" "(done_dialog 1)") ;Set action for OK.
    (action_tile "hide" "(done_dialog 4)")   ;Set action for
                                             ;PickMe.
    (setq what_next (start_dialog))          ;Display dialog box.
    ;
    (cond
      ((= what_next 4)                       ;Prompt user to
        (getpoint "\npick a point")          ;pick pt.
      )
      ((= what_next 0)
        (prompt "\nuser cancelled dialog")
      )
    )
  )
  (unload_dialog dcl_id)
  (princ)
)
NoteThe term_dialog function
terminates all dialog boxes at once but does not return a status
code, so there is no way for an application to distinguish between
hiding a nested box and canceling boxes due to an error condition.
Topics in this section
  • Requesting a Password


Requesting a Password

Functions for Hiding Dialog Boxes
Functions for Hiding Dialog Boxes
List Boxes and Pop-Up Lists
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Functions for Hiding Dialog Boxes >
Requesting a Password

The following examples show how to use a simple dialog box to request a password from users.

The getpass.dcl file defines a dialog box named passdlg, which contains two tiles: the edit_box tile where the user enters the password, and the ok_cancel tile. It uses the password_char DCL attribute to mask the text a user enters:

// GETPASS.DCL
//
passdlg : dialog {
  label = "Password Protected";
  : edit_box {
    label = "Password:";
    edit_width = 20;
    key = "password";
    password_char = "?";
  }
  ok_cancel;
}

The getpass.lsp file defines the GETPASS function. This function loads the getpass.dcl file and displays the passdlg dialog box. When a user enters text into the edit box, it is masked by the password_char character defined in the DCL file. The action assigned to the edit box ensures that the characters entered by the user are set to the pass variable:

;; GETPASS.LSP
;;
(defun GETPASS ( / dcl_id pass )
  (setq dcl_id (load_dialog "getpass.dcl"))
  (if (new_dialog "passdlg" dcl_id)
    (progn
      (action_tile "password" "(setq pass $value)")
      (start_dialog)
      (unload_dialog dcl_id)
    )
    (princ "Error: Unable to load GETPASS.DCL. ")
  )
  pass
)

The GETPASS function returns the string entered by the user.


List Boxes and Pop-Up Lists

Requesting a Password
Managing Dialog Boxes
List Operations
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
List Boxes and Pop-Up Lists

The following functions handle list boxes and pop-up lists in dialog boxes:

  • start_list
  • add_list
  • end_list

You set up the lists displayed in list boxes and pop-up lists by using a sequence of calls to these functions.

Topics in this section

  • List Operations
  • Processing List Elements


List Operations

List Boxes and Pop-Up Lists
List Boxes and Pop-Up Lists
Processing List Elements
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > List Boxes and Pop-Up Lists >
List Operations

A dialog box list operation always begins with a start_list function call. The function syntax is as follows:

(start_list key [operation [index]])

The key argument is a string that identifies the dialog box tile. The key argument is case-sensitive. The operation argument is an integer value that indicates whether you are creating a new list, changing a list, or appending to a list. The following are valid operation arguments:

Operation codes for start_list
Value | Description
1 | Change selected list contents
2 | Append new list entry
3 | Delete old list and create new list (the default)

The index argument is only used in change operations. The index indicates the list item to change by a subsequent add_list call. The first item in a list is index 0.

If you don't specify operation, it defaults to 3 (create a new list). If you do not specify an index, the index value defaults to 0.

You implement the list operations as follows:

Creating a New List (3)

After the start_list call, call add_list repeatedly to add new items to the list. End list handling by calling end_list.

Changing an Item in a List (1)

After calling start_list, call add_list once to replace the item whose index was specified in the start_list call. (If you call add_list more than once, it replaces the same item again.) End list handling by calling end_list.

Appending an Item to a List (2)

After calling start_list, call add_list to append an item to the end of the list. If you continue to call add_list, more items are appended until you call end_list.

Regardless of which list operation you are doing, you must call the three functions in sequence: start_list, then add_list (possibly more than once), and then end_list.

The mapcar function is useful for turning a “raw” AutoLISP list into a list box display. In the following example, the appnames list contains strings that you want to appear in a list box called selections. You can use this code fragment to set up the list and display it as follows:

(start_list "selections")     ;Specify the name of the list box.
(mapcar ' add_list appnames)  ;Specify the AutoLISP list.
(end_list)

Because list creation (3) is the default, this example doesn't specify it.

The value of a list_box tile is the index of the selected item (or the indexes of selected items, if multiple selections are allowed). If your program needs to know the actual text associated with an index, it must save the original list. It must also track changes to the list.

Appending list items is similar to creating a new list. If, for example, appnames has 12 items in it, and you want to append another list, called newnames, you could use the following code:

(start_list "selections" 2)
(mapcar 'add_list newnames)
(end_list)

Changing a single item requires only one add_list call. In this case, you specify the index of the item to change:

(start_list "selections" 1 5) ;Change the sixth item in the list.
(add_list "SURPRISE!")        ;Remember that the first index is 0.
(end_list)

You cannot delete a list item or insert an item without rebuilding the list from scratch.


Processing List Elements

List Operations
List Boxes and Pop-Up Lists
Image Tiles and Buttons
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > List Boxes and Pop-Up Lists >
Processing List Elements

Because the value of a list_box tile can contain leading spaces (especially if you are retrieving multiple items), do not test the value as a string comparison. Convert list_box value to an integer first with the atoi function, before processing the list box. You can also use the read function, which converts a token to an integer automatically. For example, for a list named justone that accepts only a single selection, the following code fragment checks to see if the third item in the list was selected:

(setq index ( get_tile "justone"))
(cond
 ((/= index "")               ;See if string is empty.
     (= 2 (atoi index))
                              ; Process the third entry.
     ...
     )
)

It is necessary to first check if the string is empty, because the atoi functions return 0 for an empty string as well as the string "0".

The value of a pop-up list never has a leading space, so you don't have to convert the value. Pop-up lists do not allow for multiple selection.

If the list box supports multiple selection, your program must do the conversion and step through the multiple values in the value string. The following definition of MK_LIST returns a list containing only items the user has selected from the original displist. (In this example, the display list displist is maintained as a global variable.) The MK_LIST function expects to be called with the current $value of the list box:

(defun MK_LIST (readlist / count item retlist)
  (setq count 1)
  (while (setq item (read readlist))
    (setq retlist (cons (nth item displist) retlist))
    (while (and (/= " " (substr readlist count 1))
      (/= "" (substr readlist count 1)))
      (setq count (1+ count))
    )
    (setq readlist (substr readlist count))
  )
  (reverse retlist)
)

Both preceding examples also work for the case of a single selection.


Image Tiles and Buttons

Processing List Elements
Managing Dialog Boxes
Creating Images
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Image Tiles and Buttons

AutoLISP provides functions for handling image tiles and image buttons. Examples for how to use these functions are provided in this section.

Topics in this section

  • Creating Images
  • Handling Image Buttons


Creating Images

Image Tiles and Buttons
Image Tiles and Buttons
Handling Image Buttons
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Image Tiles and Buttons >
Creating Images

The calling sequence to create images for image tiles and image buttons is similar to the list-handling sequence. The start_image function begins the creation of an image, and end_image ends it. However, the type of image to draw is specified in separate function calls, instead of arguments:

vector_image

Draws a vector (a single, straight line) in the current image.

fill_image

Draws a filled rectangle in the current image.

slide_image

Draws an AutoCAD slide in the image.

Vectors and filled rectangles are useful for simple images, such as the color swatches (filled rectangles) that the AutoCAD Select Color dialog box uses to display the user's choice of color. For complicated images, slides are more convenient. However, displaying slides can be time-consuming. If you use slides, keep them simple.

NoteIf you use slides with filled objects (such as wide polylines, solids, and 3D faces) in image tiles, the images will appear as outlines unless you make the slides from an image created with the SHADEMODE command.

The vector_image function requires that you specify absolute coordinates, while fill_image and slide_image require that you specify a starting coordinate along with a relative width and height. To do this correctly you must know the exact dimensions of the image tile or image button. Because these dimensions are usually assigned when the dialog box is laid out, the PDB feature provides functions that return the width and height of a particular tile. These dimension functions are dimx_tile and dimy_tile. You should call them before you begin creating an image. The origin of a tile, (0,0), is always the upper-left corner.

Colors can be specified as AutoCAD color numbers or as one of the logical color numbers shown in the following table. (The values and mnemonics are defined by the Autodesk Device Interface [ADI].)

Dialog box color attribute
Color number | ADI mnemonic | Meaning
-2 | BGLCOLOR | Current background of the AutoCAD graphics screen
-15 | DBGLCOLOR | Current dialog box background color
-16 | DFGLCOLOR | Current dialog box foreground color (for text)
-18 | LINELCOLOR | Current dialog box line color

In the following example, "cur_color" is an image tile you want to fill entirely with a patch of red as follows:

(setq width (dimx_tile  "cur_color")
      height (dimy_tile "cur_color"))
(start_image "cur_color")
(fill_image 0 0 width height 1)   ;1 = AutoCAD red.
(end_image)

You can use the image-drawing functions in conjunction with each other. The following code fills an image and then draws a vertical stripe over it:

(setq width (dimx_tile "stripe")
      height (dimy_tile "stripe"))
(start_image "stripe")
(fill_image 0 0 width height 3)  ;3 = AutoCAD green.
(setq x (/ width 2))             ;Center the vector vertically.
(vector_image x 0 x height 4)    ;4 = AutoCAD cyan.
(end_image)

The slides you display with slide_image can be standalone slide (SLD) files, or part of a slide library (SLB) file. If the slide is in an SLD file, you specify its name without the .sld extension (for example, "frntview"). If the slide is in a slide library, you specify the name of the library, followed by the name of the slide enclosed in parentheses. Note that the library and slide names are also specified without extensions—for example, "allviews(frntview)". The slide_image function searches for the slide or slide library file according to the current AutoCAD library search path. (See in the AutoLISP Reference.)

In the following example, the slide is in a single file called topview.sld:

(setq x (dimx_tile "view")
      y (dimy_tile "view"))
(start_image "view")
( slide_image 0 0 x y "topview")
(end_image)

Vectors in slides are often drawn in white (color number 7), which is the default background color of an image. If your image tile is blank when you first display a slide, try changing its color attribute to graphics_background. (You can also change the background of the image by preceding the slide_image call with a fill_image call.)


Handling Image Buttons

Creating Images
Image Tiles and Buttons
Application-Specific Data
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Image Tiles and Buttons >
Handling Image Buttons

You can handle an image button simply as a button—that is, you can use it to trigger a single action. However, you can also use the PDB feature to define regions of the button. With regions defined, the action taken depends on the part of the image button the user selects. The mechanism for this is straightforward: an image button's action or callback returns the (X,Y) location that the user selected. The coordinates are within the range of the particular image button tile (as returned by the dimension functions). Your application must assign a meaning to select locations by implicitly defining regions of the image. The DDVPOINT dialog box makes good use of this feature. You can view this by loading and running the ddvpoint.lsp file in the AutoCAD Support directory.

In the following example, your image button has two color swatches created by fill_image. You want to select either one or the other, depending on which region the user selects. If the image button is divided horizontally (dark above and light below), your action needs to test only the one dimension:

(action_tile "image_sel" "(pick_shade $key $value $y)")
  ...
(defun pick_shade (key val y)
  (setq threshold
    (/ ( dimy_tile  key) 2))  ;Image is divided horizontally.
  (if (> y threshold)         ;Remember that the origin is at
    (setq result "Light")     ;upper left.
  (setq result "Dark") )
)


Application-Specific Data

Handling Image Buttons
Managing Dialog Boxes
DCL Error Handling
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Application-Specific Data

The client_data_tile function assigns application-specific data to a tile. The data is available at callback time as the $data variable and must be a string. Client data is not represented in DCL; it is valid only while your application is running. Using client data is comparable to using user-defined attributes. The main difference is that user-defined attributes are read-only, while client data can change at runtime. Also, end-users can inspect user-defined attributes in the application's DCL file, but client data is invisible to them.

Because your program must maintain the list displayed by a list box (or pop-up list), client data is good for handling this information. The following modification to the MK_LIST function (shown in Processing List Elements) makes the list an argument:

(defun MK_LIST (readlist displist / )

This code eliminates the need for a global list variable. The following calls in the main part of the dialog box handler associate a short list with the tile by calling client_data_tile, and then pass that list to MK_LIST by means of an action expression as follows:

(client_data_tile
  "colorsyslist"
  "Red-Green-Blue Cyan-Magenta-Yellow Hue-Saturation-Value"
)
(action_tile
  "colorsyslist"
  "(setq usrchoice (mk_list $value $data))"
)


DCL Error Handling

Application-Specific Data
Managing Dialog Boxes
Setting the Auditing Level to Affect Error Messages
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
DCL Error Handling

The PDB feature checks a DCL file for errors the first time you load it. If AutoCAD encounters a syntax error, a misuse of attributes, or any other error (such as failure to specify a key attribute for an active tile), the PDB does not load the DCL file. Instead, AutoCAD either displays one or more dialog boxes alerting you to the error, or writes a list of errors to a text file called acad.dce. If AutoCAD writes the error messages to acad.dce, it alerts you to this with a message similar to the following:

You can inspect the contents of acad.dce to find the problem. AutoCAD places the acad.dce file in the current working directory. When AutoCAD reads a DCL file successfully, it deletes the acad.dce file.

If your application uses multiple DCL files, the acad.dce file is overwritten (or deleted if no errors occur) when each new file is loaded. When you test the program, acad.dce shows errors (if any) from only the DCL file most recently read. It is recommended that you use the VLISP DCL Preview feature to debug your DCL files (see Displaying Dialog Boxes with Visual LISP). You can also load and debug each file manually in AutoCAD with the load_dialog function. The following load_dialog function loads the DCL file hellofile.dcl:

Command:  (load_dialog "hellofile")

3

If the dialog box loads successfully, load_dialog returns a positive integer that identifies the DCL file. You pass this value to the new_dialog function to initialize individual dialog boxes in the file.

The new_dialog function returns T if it succeeds; otherwise it returns nil. If new_dialog returns T, call the start_dialog function to display the dialog box.

Once you've debugged each DCL file, you can load your program and test the dialog boxes in combination. If your program calls a restricted function between the start_dialog and done_dialog calls, AutoCAD terminates all dialog boxes and displays the following error message:

AutoCAD rejected function

SeeFunctions Restricted When a Dialog Box Is Open for information on which functions are restricted.

Topics in this section

  • Setting the Auditing Level to Affect Error Messages


Setting the Auditing Level to Affect Error Messages

DCL Error Handling
DCL Error Handling
Dialog Box Function Summary
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > DCL Error Handling >
Setting the Auditing Level to Affect Error Messages

The level of semantic auditing affects which messages AutoCAD issues for a DCL file (see Semantic Auditing of DCL Files). For example, the hidedcl dialog box defined in Functions for Hiding Dialog Boxes is displayed without any warnings, if you use the default audit level. If you set the audit level to 3, though, AutoCAD displays an alert dialog box with a warning message. You can see this for yourself by inserting the following line at the beginning of hidedcl:

dcl_settings : default_dcl_settings { audit_level = 3; }

Try using the VLISP DCL Preview feature to view the dialog box defined in hidedcl. You will be alerted to view the acad.dce file, which contains the following messages:

=== DCL semantic audit of C:/PROGRA~1/AUTOCA~1/VLISP/$vld$.dcl ===
Hint in "hidedcl". (widget type = text, key = "message")
    fixed_height = true is probably redundant.

At lower (less discriminating) levels of semantic auditing, AutoCAD does not look for redundant attribute definitions and the dialog box displays normally.

Remove the fixed_height = true statement from the DCL to correct the situation AutoCAD is warning you about.


Dialog Box Function Summary

Setting the Auditing Level to Affect Error Messages
Managing Dialog Boxes
Function Sequence
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes >
Dialog Box Function Summary

This section summarizes the steps required in a typical dialog box handling function. It also describes a sample application you can refer to when designing and implementing your own dialog box functions.

Topics in this section

  • Function Sequence
  • The Sample Block Definition Dialog Box


Function Sequence

Dialog Box Function Summary
Dialog Box Function Summary
The Sample Block Definition Dialog Box
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Dialog Box Function Summary >
Function Sequence

The following demonstrates the typical function sequence:

  1. Load the DCL file with a load_dialog call.
  2. Call new_dialog to display a particular dialog box.

    Be sure to check the value returned by new_dialog. Calling start_dialog when the new_dialog call has failed can have unpredictable results.

  3. Initialize the dialog box by setting up tile values, lists, and images. Initialize also when you call action_tile to set up action expressions or callback functions. Other functions typically called at this time are set_tile and mode_tile for general tile values and states, start_list, add_list, and end_list for list boxes, and the dimension functions with start_image, vector_image, fill_image, slide_image, and end_image for images. At this time you can also call client_data_tile to associate application-specific data with the dialog box and its components.
  4. Call start_dialog to turn control over to the dialog box, so that the user can enter input.
  5. Process user input from within your actions (callbacks). Process input when you are most likely to use get_tile, get_attr, set_tile, and mode_tile.

    The user presses an exit button, causing an action to call done_dialog, which causes start_dialog to return a value. At this point, unload the DCL file by calling unload_dialog.

    This scheme handles only one dialog box and one DCL file at a time. Applications usually have multiple dialog boxes. The easiest and quickest way to handle these dialog boxes is to save all of them in a single DCL file. The load_dialog call then loads all dialog boxes at once, and you can call new_dialog for any dialog box. If memory is limited, however, you may need to create multiple DCL files and use unload_dialog to remove one set of dialog boxes from memory before you load another set.


The Sample Block Definition Dialog Box

Function Sequence
Dialog Box Function Summary
Programmable Dialog Box Reference
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Managing Dialog Boxes > Dialog Box Function Summary >
The Sample Block Definition Dialog Box

The sample application bmake.lsp and its associated bmake.dcl file illustrate a number of useful dialog box techniques. These files are in the AutoCAD Support directory. The bmake application is essentially an interactive interface to the entmake function. You can use it to define new blocks and to view the names of existing blocks. Some of the techniques illustrated by bmake are

  • Hiding dialog boxes by defining special status codes for done_dialog to pass to start_dialog. See the main loop of the C:BMAKE function (following the load_dialog and action_tile calls).
  • Using a toggle to enable or disable another tile. See the definition of the DO_UNNAMED function.
  • Building a list for a list box. See the PAT_MATCH and SORT functions.
  • Displaying the standard AutoCAD Help dialog box. See the DO_HELP function.

Aside from demonstrating dialog box techniques, bmake illustrates good design.


Programmable Dialog Box Reference

The Sample Block Definition Dialog Box
Working with Programmable Dialog Boxes
Tile Attributes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes >
Programmable Dialog Box Reference

You can use attributes to work with dialog boxes.

This chapter lists and describes all the dialog control language (DCL) tiles and their associated attributes, and summarizes the Visual LISP® functions available for working with programmable dialog boxes.

Topics in this section

  • Tile Attributes
  • Synopsis of Predefined Attributes
  • DCL Attribute Catalog
  • action
  • alignment
  • allow_accept
  • aspect_ratio
  • big_increment
  • children_alignment
  • children_fixed_height
  • children_fixed_width
  • color
  • edit_limit
  • edit_width
  • fixed_height
  • fixed_width
  • fixed_width_font
  • height
  • initial_focus
  • is_bold
  • is_cancel
  • is_default
  • is_enabled
  • is_tab_stop
  • key
  • label
  • layout
  • list
  • max_value
  • min_value
  • mnemonic
  • multiple_select
  • password_char
  • small_increment
  • tabs
  • tab_truncate
  • value
  • width
  • Functional Synopsis of DCL Tiles
  • DCL Tile Catalog
  • boxed_column
  • boxed_radio_column
  • boxed_radio_row
  • boxed_row
  • button
  • column
  • concatenation
  • dialog
  • edit_box
  • errtile
  • image
  • image_button
  • list_box
  • ok_only
  • ok_cancel
  • ok_cancel_help
  • ok_cancel_help_errtile
  • ok_cancel_help_info
  • paragraph
  • popup_list
  • radio_button
  • radio_column
  • radio_row
  • row
  • slider
  • text
  • text_part
  • toggle
  • spacer
  • spacer_0
  • spacer_1
  • Programmable Dialog Box Function Synopsis


Tile Attributes

Programmable Dialog Box Reference
Programmable Dialog Box Reference
Attribute Types
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
Tile Attributes

A tile's attributes define its layout and functionality. An attribute is similar to a programming language variable: it consists of a name and a value.

Topics in this section

  • Attribute Types
  • Restricted Attributes
  • User-Defined Attributes


Attribute Types

Tile Attributes
Tile Attributes
Restricted Attributes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Tile Attributes >
Attribute Types

The value of an attribute must be one of the following data types:

Integer

Numeric values (both integers and real numbers) that represent distances, such as the width or height of a tile, are expressed in character-width or character-height units.

Real Number

A fractional real number must have a leading digit: for example, 0.1, not .1.

Quoted String

A quoted string consists of text enclosed in quotation marks (""). Attribute values are case-sensitive: B1 is not the same as b1. If the string must contain a quotation mark, precede the quotation mark character with a backslash (\"). Quoted strings can contain other control characters as well. The characters recognized by DCL are shown in the following table:

Control characters allowed in DCL strings

Control character

Meaning

\"

quote (embedded)

\\

backslash

\n

newline

\t

horizontal tab

Reserved Word

A reserved word is an identifier made up of alphanumeric characters, beginning with a letter. For example, many attributes require a value of either true or false. Reserved words are also case-sensitive: True does not equal true.

Like reserved words and strings, attribute names are case-sensitive; for example, you cannot assign a width by calling it Width.

Application programs always retrieve attributes as strings. If your application uses numeric values, it must convert them to and from string values. For more information on handling tile values within an AutoLISP® program, see Handling Tiles.

Some attributes, such as width and height, are common to all tiles. Attribute specifications are optional. Many attributes have default values that are used if the attribute is not specified. Other attributes are specifically meant for certain kinds of tiles—for example, the background color of an image. If you attempt to assign this attribute to a different kind of tile, AutoCAD® may report an error. Usually, it ignores the attribute.


Restricted Attributes

Attribute Types
Tile Attributes
User-Defined Attributes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Tile Attributes >
Restricted Attributes

The following tile attributes are restricted. Do not use them in your DCL files:

  • horizontal_margin
  • vertical_margin
  • type


User-Defined Attributes

Restricted Attributes
Tile Attributes
Synopsis of Predefined Attributes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Tile Attributes >
User-Defined Attributes

When defining tiles, you can assign your own attributes. The name of the attribute can be any valid name that does not conflict with the standard, predefined attributes described in Restricted Attributes and summarized in Synopsis of Predefined Attributes. An attribute name, like a keyword, can contain letters, numbers, or the underscore (_), and must begin with a letter.

If a user-defined attribute name conflicts with a predefined attribute, the PDB feature does not recognize the attribute as a new one, and attempts to use the value you assign it with the standard attribute. This can be very hard to debug.

The values you assign to the attribute, and their meanings, are defined by your application. Values for user-defined attributes must conform to the types described in Tile Attributes.

Defining attributes is comparable to defining application-specific client data. Both techniques enable the PDB feature to manage data you supply. User-defined attributes are read-only, that is, they are static while the dialog box is active. If you need to change the values dynamically, you must use client data at runtime. Also, end users can inspect the value of user-defined attributes in the application's DCL file, but client data remains invisible.

The definition of the AutoCAD Drawing Aids dialog box defines its own attribute, errmsg, which has a unique string value for each tile. A common error handler uses the value of errmsg when it displays a warning. For example, the tile could assign the following value to errmsg:

errmsg = "Grid Y Spacing";

If the user enters an unusable value, such as a negative number, AutoCAD displays the following error message:

Invalid Grid Y Spacing.

The word Invalid and the trailing period (.) are supplied by the error handler.

User-defined attributes can also be used for limits on the value of a tile and the name of a subdialog box that the tile activates (seeNesting Dialog Boxes).


Synopsis of Predefined Attributes

User-Defined Attributes
Programmable Dialog Box Reference
DCL Attribute Catalog
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
Synopsis of Predefined Attributes

This section lists the attributes defined by the PDB feature. The following table summarizes the predefined attributes in alphabetical order. The attributes are described in detail in User-Defined Attributes.

Predefined attributes
Attribute name | Associated with | Meaning (if specified or true)
action | All active tiles | AutoLISP action expression
alignment | All tiles | Horizontal or vertical position in a cluster
allow_accept | edit_box, image_button, list_box | Activates is_default button when this tile is selected
aspect_ratio | image, image_button | Aspect ratio of an image
big_increment | slider | Incremental distance to move
children_alignment | row, column, radio_row, radio_column, boxed_row, boxed_column, boxed_radio_row, boxed_radio_column | Alignment of a cluster's children
children_fixed_ height | row, column, radio_row, radio_column, boxed_row, boxed_column, boxed_radio_row, boxed_radio_column | Height of a cluster's children doesn't grow during layout
children_fixed_ width | row, column, radio_row, radio_column, boxed_row, boxed_column, boxed_radio_row, boxed_radio_column | Width of a cluster's children doesn't grow during layout
color | image, image_button | Background (fill) color of an image
edit_limit | edit_box | Maximum number of characters users can enter
edit_width | edit_box, popup_list | Width of the edit (input) portion of the tile
fixed_height | All tiles | Height doesn't grow during layout
fixed_width | All tiles | Width doesn't grow during layout
fixed_width_font | list_box, popup_list | Displays text in a fixed pitch font
height | All tiles | Height of the tile
initial_focus | Dialog | Key of the tile with initial focus
is_bold | Text | Displays as bold
is_cancel | Button | Button is activated when the cancel key—usually ESC—is pressed
is_default | Button | Button is activated when the accept key—usually ENTER—is pressed
is_enabled | All active tiles | Tile is initially enabled
is_tab_stop | All active tiles | Tile is a tab stop
key | All active tiles | Tile name used by the application
label | boxed_row, boxed_column, boxed_radio_row, boxed_radio_column, button, dialog, edit_box, list_box, popup_list, radio_button, text, toggle | Displayed label of the tile
layout | slider | Whether the slider is horizontal or vertical
list | list_box, popup_list | Initial values to display in list
max_value | slider | Maximum value of a slider
min_value | slider | Minimum value of a slider
mnemonic | all active tiles | Mnemonic character for the tile
multiple_select | list_box | List box allows multiple items to be selected
password_char | edit_box | Masks characters entered in edit_box
small_increment | slider | Incremental distance to move
tabs | list_box, popup_list | Tab stops for list display
tab_truncate | list_box, popup_list | Truncates text that is larger than the associated tab stop
value | Text, active tiles (except buttons and image buttons) | Tile's initial value
width | All tiles | Width of the tile


DCL Attribute Catalog

Synopsis of Predefined Attributes
Programmable Dialog Box Reference
action
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
DCL Attribute Catalog

DCL tile attributes are described in detail in this section. The attributes are listed alphabetically.


action

DCL Attribute Catalog
Programmable Dialog Box Reference
alignment
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
action
action = "(function)";

Specifies an AutoLISP expression to perform an action when this tile is selected. Also known as a callback. For some kinds of tiles, an action can also occur when the user switches focus to a different tile.

The possible value is a quoted string that is a valid AutoLISP® expression. A tile can have only one action. If the application assigns it an action (with action_tile), this overrides the action attribute.

NoteYou cannot call the AutoLISP command function from the action attribute.


alignment

action
Programmable Dialog Box Reference
allow_accept
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
alignment
alignment = position;

Specifies the horizontal or vertical positioning (justification) of a tile within its cluster.

For a tile that is a child of a column, the possible values are left, right, or centered (default is left).

For a tile that is a child of a row, the possible values are top, bottom, or centered (default is centered).

You cannot specify the alignment along the long axis of a cluster. The first and last tiles in the cluster always align themselves with the ends of the column or row. Other tiles in the cluster are distributed evenly unless you adjust the distribution by using padding insertion points (see spacer_0).


allow_accept

alignment
Programmable Dialog Box Reference
aspect_ratio
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
allow_accept
allow_accept = true-false;

Specifies whether the tile is activated when the user presses the accept key (usually ENTER). If true and the user presses the accept key, the default button (if any) is pressed. The default button is the button tile whose is_default attribute is set to true. The allow_accept attribute defaults to false.


aspect_ratio

allow_accept
Programmable Dialog Box Reference
big_increment
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
aspect_ratio
aspect_ratio = real;

Specifies the ratio of the width of the image to its height (width divided by height). If zero (0.0), the tile is fitted to the size of the image.

Possible values are floating-point values (default: none).


big_increment

aspect_ratio
Programmable Dialog Box Reference
children_alignment
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
big_increment
big_increment = integer;

Specifies the value used by the slider's incremental controls. The default value of big_increment is one-tenth of the total range. The value must be within the range specified by min_value and max_value.


children_alignment

big_increment
Programmable Dialog Box Reference
children_fixed_height
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
children_alignment
children_alignment = position;

Specifies the default alignment (similar to alignment) for all tiles in a cluster. Does not override a child's alignment attribute, if alignment is specified explicitly.

For columns, possible values are left, right, or centered (default: left).

For rows, possible values are top, bottom, or centered (default: centered).


children_fixed_height

children_alignment
Programmable Dialog Box Reference
children_fixed_width
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
children_fixed_height
children_fixed_height = true-false;

Specifies the default height (similar to height) for all tiles in a cluster. Does not override a child's height attribute, if it is specified explicitly.

Possible values are true or false (default: false).

NoteUse the fixed_ attributes with discretion. Inconsistent overriding of defaults results in inconsistent layouts.


children_fixed_width

children_fixed_height
Programmable Dialog Box Reference
color
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
children_fixed_width
children_fixed_width = true-false;

Specifies the default width (similar to width) for all tiles in a cluster. Does not override a child's width attribute, if it is specified explicitly.

Possible values are true or false (default: false).

NoteUse the fixed_ attributes with discretion. Inconsistent overriding of defaults results in inconsistent layouts.


color

children_fixed_width
Programmable Dialog Box Reference
edit_limit
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
color
color = colorname;

Specifies the background (fill) color of the image. Possible values are an integer or reserved word (default: 7) specified as an AutoCAD color number or as one of the symbolic names shown in the following table:

Symbolic names for colors
Symbolic name | Meaning
dialog_line | Current dialog box line color
dialog_foreground | Current dialog box foreground color (for text)
dialog_background | Current dialog box background color
graphics_background | Current background of the AutoCAD graphics screen (usually equivalent to 0)
black | AutoCAD color = 0 (black) (appears light on a black background)
red | AutoCAD color = 1 (red)
yellow | AutoCAD color = 2 (yellow)
green | AutoCAD color = 3 (green)
cyan | AutoCAD color = 4 (cyan)
blue | AutoCAD color = 5 (blue)
magenta | AutoCAD color = 6 (magenta)
white graphics_foreground | AutoCAD color = 7 (white) (appears black on a light background)

The symbolic names graphics_background and graphics_foreground are provided as alternatives to the names black and white. The use of a specific color can be confusing because the color that is actually displayed varies depending on the current AutoCAD configuration. Also, vectors in slides that you display in an image are often drawn in black or white. If your image tile is blank when you first display it, try changing its color to graphics_background or graphics_foreground.


edit_limit

color
Programmable Dialog Box Reference
edit_width
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
edit_limit
edit_limit = integer;

Specifies the maximum number of characters a user is allowed to enter in the edit box. A possible value is an integer (default: 132). When the user reaches this limit, AutoCAD rejects additional characters (except for BACKSPACE or DEL). The maximum edit limit allowed is 256 characters.


edit_width

edit_limit
Programmable Dialog Box Reference
fixed_height
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
edit_width
edit_width = number;

Specifies the width in character-width units of the edit (input) portion of the box—the actual boxed portion of the edit_box tile. Possible values are an integer or a real number. If edit_width is not specified or is zero, and the width of the tile is not fixed, the box expands to fill the available space. If edit_width is nonzero, then the box is right-justified within the space occupied by the tile. If it's necessary to stretch the tile for layout purposes, the PDB feature inserts white space between the label and the edit portion of the box.


fixed_height

edit_width
Programmable Dialog Box Reference
fixed_width
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
fixed_height
fixed_height = true-false;

Specifies if a tile's height is allowed to fill the available space. If this attribute is true, the tile does not fill the extra space that becomes available in the layout/alignment process.

Possible values are true or false (default: false).


fixed_width

fixed_height
Programmable Dialog Box Reference
fixed_width_font
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
fixed_width
fixed_width = true-false;

Specifies if a tile's width is allowed to fill the available space. If this attribute is true, the tile does not fill the extra space that becomes available in the layout/alignment process.

Possible values are true or false (default: false).


fixed_width_font

fixed_width
Programmable Dialog Box Reference
height
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
fixed_width_font
fixed_width_font = true-false;

Specifies whether a list box or pop-up list will display text in a fixed pitch font. This allows for easier spacing and tab alignment of -columns.

Possible values are true or false (default: false).


height

fixed_width_font
Programmable Dialog Box Reference
initial_focus
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
height
height = number;

Specifies the height of a tile. Possible values are an integer or a real number representing the distance in character height units. Do not specify this value unless the assigned defaults do not have an acceptable appearance. You must specify, however, the height of image tiles and image buttons.

The height attribute specifies the minimum height of a tile. This dimension can be expanded when the tile is laid out, unless the height is fixed by one of the fixed_ attributes. Defaults are dynamically assigned based on layout constraints.

Character-height units are defined as the maximum height of screen characters (including line spacing).


initial_focus

height
Programmable Dialog Box Reference
is_bold
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
initial_focus
initial_focus = "string";

Specifies the key of the tile within the dialog box that receives the initial keyboard focus. Possible value is a quoted string (no default).


is_bold

initial_focus
Programmable Dialog Box Reference
is_cancel
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
is_bold
is_bold = true-false;

Specifies whether the text is displayed in bold characters. Possible values are true or false (default: false). If true, the text is displayed in bold characters.


is_cancel

is_bold
Programmable Dialog Box Reference
is_default
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
is_cancel
is_cancel = true-false;

Specifies whether the button is selected when the user presses the ESC key. Possible values are true or false (default: false).

If the action expression for buttons with the is_cancel attribute set to true does not exit the dialog box (does not call done_dialog), the dialog box is automatically terminated after the action expression has been carried out, and the DIASTAT system variable is set to 0.

Only one button in a dialog box can have the is_cancel attribute set to true.


is_default

is_cancel
Programmable Dialog Box Reference
is_enabled
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
is_default
is_default = true-false;

Specifies whether the button is the default button selected (“pushed”) when the user presses the accept key. Possible values are true or false (default: false). If the user is in an edit_box, list_box, or image_button that has the allow_accept attribute set to true, the default button is also selected if the user presses the accept key or (for list boxes and image buttons) double-clicks. The default button is not selected by the accept key if another button has focus. In this case, the button that has focus is the one selected.

Only one button in a dialog box can have the is_default attribute set to true.


is_enabled

is_default
Programmable Dialog Box Reference
is_tab_stop
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
is_enabled
is_enabled = true-false;

Specifies whether or not the tile is initially available. Possible values are true or false (default: true). If false, the tile is unavailable and appears grayed out.


is_tab_stop

is_enabled
Programmable Dialog Box Reference
key
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
is_tab_stop
is_tab_stop = true-false;

Specifies whether the tile receives keyboard focus when the user moves between tiles by pressing the TAB key. Possible values are true or false (default: true). If the tile is disabled, it is not a tab stop even if this attribute is true. If false, the tile is not a tab stop.


key

is_tab_stop
Programmable Dialog Box Reference
label
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
key
key = "string";

Specifies a name that the program uses to refer to this specific tile. Possible value is a quoted string (no default). Within a particular dialog box, each key value must be unique. This string is case-sensitive: if you specify the key as BigTile, you cannot reference it as bigtile.

Because the value of a key is not visible to the user, its name can be whatever you choose (as long as it is unique to the dialog box). For the same reason, key attributes do not need to be translated for applications offered in multiple languages.


label

key
Programmable Dialog Box Reference
layout
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
label
label = "string";

Specifies the text displayed within the tile. Possible value is a quoted string (default: a blank string, " "). The placement of label text is tile-specific.

The label attribute can specify a mnemonic character for the tile. The mnemonic is underlined in the tile's label.

Any character in a label string that is preceded by an ampersand (&) becomes the mnemonic. The character doesn't have to be unique to the dialog box. If more than one tile has the same mnemonic, the user presses that key to cycle through the tiles sequentially.

Mnemonics change focus but do not select a tile. If the user specifies a mnemonic key for a tile that contains a group of items, such as a cluster or a list box, the focus is put on the first item in the tile that is a tab stop. Any active tile is a tab stop unless its is_tab_stop attribute is set to false.

NoteThe mnemonic attribute also specifies a mnemonic character.


layout

label
Programmable Dialog Box Reference
list
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
layout
layout = position;

Specifies the orientation of a slider. Possible values are horizontal or vertical (default: horizontal). For horizontal sliders, the value increases from left to right. For vertical sliders, the value increases from bottom to top.


list

layout
Programmable Dialog Box Reference
max_value
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
list
list = "string";

Specifies the initial set of lines (choices) to be placed in the popup_list or list_box. Possible value is a quoted string (no default). Lines are separated by a new line symbol (\n). Tab characters (\t) can occur within each line.


max_value

list
Programmable Dialog Box Reference
min_value
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
max_value
max_value = integer;

Specifies the upper range of values that a slider returns. Default maximum value is 10000. This value must be a signed, 16-bit integer no greater than 32767.


min_value

max_value
Programmable Dialog Box Reference
mnemonic
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
min_value
min_value = integer;

Specifies the lower range of values that a slider returns. Default minimum value is 0. This value must be a signed, 16-bit integer no less than -32768. The min_value can be greater than the max_value.


mnemonic

min_value
Programmable Dialog Box Reference
multiple_select
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
mnemonic
mnemonic = "char";

Specifies a keyboard mnemonic character for the tile. The mnemonic is underlined in the tile's label. A possible value is a quoted string of a single character (no default). The character must be one of the letters in the tile's label. The character doesn't have to be unique to the dialog box. If more than one tile has the same mnemonic, the user presses that key to cycle through the tiles sequentially.

From the user's point of view, mnemonics aren't case-sensitive. For example, if a button's mnemonic character is A,entering either a or A gives the A button focus. However, in the DCL file the mnemonic must be one of the characters in the tile's label, and it must be capitalized as it appears in the label string.

Mnemonics change focus. If the user specifies a mnemonic key for a tile that contains a group of items, such as a cluster or a list box, the focus is put on the first item in the tile that is a tab stop. Any active tile is a tab stop unless its is_tab_stop attribute is set to false.

NoteThe label attribute can also specify a mnemonic character.


multiple_select

mnemonic
Programmable Dialog Box Reference
password_char
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
multiple_select
multiple_select = true-false;

Specifies whether multiple items in the list_box can be selected (highlighted) at the same time. Possible values are true or false (default: false). If true, multiple items can be selected at a time.


password_char

multiple_select
Programmable Dialog Box Reference
small_increment
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
password_char
password_char = "char";

Specifies the character to be used to mask user input. If password_char is specified and is not null, that character is displayed in the edit box instead of the characters entered by the user. The use of this attribute has no effect on your application's retrieval of the value entered by the user; it alters only the display of the characters in the edit box.

For an example of using the password_char attribute in an application, see Requesting a Password.


small_increment

password_char
Programmable Dialog Box Reference
tabs
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
small_increment
small_increment = integer;

Specifies the value used by the slider's incremental controls. Default value of small_increment is one one-hundredth the total range. The value must be within the range specified by min_value and max_value. This attribute is optional.


tabs

small_increment
Programmable Dialog Box Reference
tab_truncate
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
tabs
tabs = "string";

Specifies the placement of tabs in character width units. Possible value is a quoted string containing integers or floating-point numbers, separated by spaces (no default). These values are used for vertically aligning columns of text in a popup_list or list_box.

For example, the following code specifies a tab stop at every 8 characters.

tabs = "8 16 24 32";


tab_truncate

tabs
Programmable Dialog Box Reference
value
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
tab_truncate
tab_truncate = true-false;

Specifies whether the text in a list box or pop-up list is truncated if it is larger than the associated tab stop. Possible values are true or false (default: false).


value

tab_truncate
Programmable Dialog Box Reference
width
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
value
value = "string";

Specifies the initial value of a tile. Possible value is a quoted string. The meaning of a tile's value varies depending on the kind of tile. The value of a tile can change at runtime through user input or set_tile calls.

The value attribute of a tile is not considered when the dialog box is laid out. After the layout is finished and the dialog box has been displayed, new_dialog uses the value attributes to initialize each tile in the dialog box. A tile's value attribute has no effect on the size or spacing of tiles in the dialog box.


width

value
Programmable Dialog Box Reference
Functional Synopsis of DCL Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
width
width = number;

Specifies the width of a tile. Possible values are an integer or a real number representing the distance in character-width units. Do not specify this value unless the assigned defaults don't provide acceptable appearance. You must specify, however, the width of image tiles and image buttons.

The width of a tile specifies a minimum width. This dimension can be expanded when the tile is laid out unless the width is fixed by one of the fixed_ attributes. Defaults are dynamically assigned based on layout constraints.

Character width units are defined as the average width of all uppercase and lowercase alphabetic characters, or the screen width divided by 80, whichever is less (average width is (width(A .. Z) + width (a .. z)))/52 ).


Functional Synopsis of DCL Tiles

width
Programmable Dialog Box Reference
Predefined Active Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
Functional Synopsis of DCL Tiles

This section presents the DCL tiles in functional groupings.

Topics in this section

  • Predefined Active Tiles
  • Tile Clusters
  • Decorative and Informative Tiles
  • Text Clusters
  • Dialog Box Exit Buttons and Error Tiles
  • Restricted Tiles


Predefined Active Tiles

Functional Synopsis of DCL Tiles
Functional Synopsis of DCL Tiles
Tile Clusters
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Functional Synopsis of DCL Tiles >
Predefined Active Tiles

The AutoCAD PDB feature has a set of built-in, or predefined, tiles that can be used by themselves or as the basis for more complex tiles. Their definitions appear as comments within the base.dcl file. (See The base.dcl and acad.dcl Files.)

When the user chooses an active tile—a button, for example—the dialog box responds by notifying the application controlling the dialog box. Any predefined active tile can have an associated action. The effect of an action can be visible to the user or can be purely internal (for example, a status update). Actions are accompanied by a reason code that indicates what triggered the action. The meaning of the reason depends on which kind of tile triggered it. The following tiles are selectable, active tiles:

button | popup_list
edit_box | radio_button
image_button | slider
list_box | toggle


Tile Clusters

Predefined Active Tiles
Functional Synopsis of DCL Tiles
Decorative and Informative Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Functional Synopsis of DCL Tiles >
Tile Clusters

You can group tiles into composite rows or columns (known collectively as clusters). For layout purposes, a cluster is treated as a single tile. The row or column can be boxed, with an optional label (a cluster without a box cannot be labeled).

Users cannot select a cluster, only individual tiles within the cluster. Clusters cannot have actions assigned to them, with the exception of radio rows and radio columns. The following tiles define clusters:

boxed_column | dialog
boxed_radio_column | radio_column
boxed_radio_row | radio_row
boxed_row | row
column |


Decorative and Informative Tiles

Tile Clusters
Functional Synopsis of DCL Tiles
Text Clusters
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Functional Synopsis of DCL Tiles >
Decorative and Informative Tiles

The tiles listed below do not cause actions and cannot be selected. They are provided to display information or for visual emphasis, or to assist you in laying out the dialog box.

image | spacer_0
text | spacer_1
spacer |


Text Clusters

Decorative and Informative Tiles
Functional Synopsis of DCL Tiles
Dialog Box Exit Buttons and Error Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Functional Synopsis of DCL Tiles >
Text Clusters

A text tile is surrounded by margin space (like any other kind of tile), which presents a problem when you want to combine pieces of text. For example, assume you want to display the following message:

The time is now 0800 hours and 37 seconds.

The actual values (0800 and 37) are supplied by your program. You can do this by creating a concatenated line of text built out of text_part tiles. You can also use text parts vertically to create a paragraph that doesn't have too much space between the lines.

The following text cluster tiles are prototypes defined in the base.dcl file.


Dialog Box Exit Buttons and Error Tiles

Text Clusters
Functional Synopsis of DCL Tiles
Restricted Tiles
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Functional Synopsis of DCL Tiles >
Dialog Box Exit Buttons and Error Tiles

The base.dcl file provides standard button subassemblies for exiting (or “retiring”) a dialog box. Use these standard versions to maintain a consistent appearance across applications.

You can customize the text in these buttons by using the prototype retirement_button as described in Customizing Exit Button Text.


Restricted Tiles

Dialog Box Exit Buttons and Error Tiles
Functional Synopsis of DCL Tiles
DCL Tile Catalog
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Functional Synopsis of DCL Tiles >
Restricted Tiles

Your DCL files should not use the tiles cluster or tile. Also, do not use the basic exit button types (cancel_button, help_button, info_button, and ok_button) unless you redefine the standard exit button subassemblies as described in Dialog Box Exit Buttons and Error Tiles.


DCL Tile Catalog

Restricted Tiles
Programmable Dialog Box Reference
boxed_column
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
DCL Tile Catalog

This section describes all the predefined DCL tiles. The syntax statement, which follows the tile name, lists all the attributes associated with that tile. Any specific attribute functionality is noted following the tile's description.


boxed_column

DCL Tile Catalog
Programmable Dialog Box Reference
boxed_radio_column
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
boxed_column
: boxed_column {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

A boxed column has a border around it. A dialog box is laid out like a boxed column. If a boxed column is assigned a label, the label appears embedded in the top border. If the label is absent, blank (""), or null (""), only the box is displayed.

label

Appears as a title. Spacing between a blank and a null label might be different. (See Fixing the Spacing Around a Boxed Row or Column.)


boxed_radio_column

boxed_column
Programmable Dialog Box Reference
boxed_radio_row
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
boxed_radio_column

: boxed_radio_column {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

A boxed radio column has a border around it. Treat the label the same way that you would treat the label of a boxed column.

label

Appears as a title. If the label is absent, blank (the default), or null (""), only the box appears. Spacing between a blank and a null label might be different. (See Fixing the Spacing Around a Boxed Row or Column .)

value

Specifies the key of the currently selected radio button (the one whose value is "1").


boxed_radio_row

boxed_radio_column
Programmable Dialog Box Reference
boxed_row
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
boxed_radio_row

: boxed_radio_row {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

A boxed radio row has a border around it. You treat the label the same way that you would treat the label of a boxed row.

label

Appears as a title. If the label is absent, blank (the default), or null (""), only the box appears. Spacing between a blank and a null label might be different. (See Fixing the Spacing Around a Boxed Row or Column.)

value

Specifies the key of the currently selected radio button (the one whose value is "1").


boxed_row

boxed_radio_row
Programmable Dialog Box Reference
button
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
boxed_row

: boxed_row {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

A boxed row has a border around it. If a boxed row has a label, the label appears embedded in it.

label

Appears as a title. If the label is absent, blank (the default), or null (""), only the box appears. Spacing between a blank and a null label might be different. (See Fixing the Spacing Around a Boxed Row or Column.)


button

boxed_row
Programmable Dialog Box Reference
column
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
button
: button {
   action alignment fixed_height fixed_width
   height is_cancel is_default is_enabled
   is_tab_stop key label mnemonic width
}

A button tile resembles a push button. The button's label specifies text that appears inside the button. Buttons are appropriate for actions that are immediately visible to the user such as leaving the dialog box, or going into a subdialog box.

Dialog boxes must include an OK button (or its equivalent) for the user to press after using (or reading) the box. Many dialog boxes also include a Cancel button that enables the user to leave the dialog box without making any changes.

Dialog boxes should use the standard exit button subassemblies described in Dialog Box Exit Buttons and Error Tiles. These subassemblies guarantee that the attributes described in this section are correctly assigned.

NoteIf you make the default button and the cancel button the same, you must make sure at least one other exit button is associated with an action that calls done_dialog. Otherwise, the dialog box is always canceled.
label

Specifies the text that appears in the button.


column

button
Programmable Dialog Box Reference
concatenation
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
column
: column {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

Tiles in a column are laid out vertically in the order in which they appear in the DCL file. A column can contain any kind of tile (except for solitary radio buttons), including rows and other columns.

A column without a box has no additional attributes beyond the standard layout attributes.


concatenation

column
Programmable Dialog Box Reference
dialog
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
concatenation
: concatenation {
}

A concatenation is a line of text made up of multiple, concatenated text_part tiles. This is useful when you want to insert text that can change at runtime into a standard message. There is a margin around the concatenation as a whole.

The concatenation tile is defined in the base.dcl file. See paragraph for an example that uses concatenation.


dialog

concatenation
Programmable Dialog Box Reference
edit_box
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
dialog
: dialog {
   initial_focus label value
}

A dialog is the tile that defines the dialog box. You should not specify both a label and value attribute: the value attribute overrides the label attribute.

label

Specifies the optional title displayed in the title bar of the dialog box.

value

Specifies a string to display as the optional dialog box title. However, the value isn't inspected at layout time, so if you assign the title this way, make sure the dialog box is wide enough or the text might be truncated.

For a dialog, the label and value are equivalent except for layout considerations. To change the title (see in at runtime, use the set_tile function the AutoLISP Reference).

initial_focus

Specifies the key of the tile that receives the initial keyboard focus.


edit_box

dialog
Programmable Dialog Box Reference
errtile
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
edit_box
: edit_box {
   action alignment allow_accept edit_limit
   edit_width fixed_height fixed_width height
   is_enabled is_tab_stop key label mnemonic
   value width password_char
}

An edit box is a field that enables the user to enter or edit a single line of text. An optional label can appear to the left of the box. If the entered text is longer than the length of the edit box, the edit box scrolls horizontally.

Left-justifying the label and right-justifying the edit box makes it easier to align edit_box tiles vertically.

label

Appears as a title. If specified, the label is left-justified within the width of the edit_box tile.

value

The initial ASCII value placed in the box. It is displayed left-justified within the edit (input) part of the box. The value of an edit box is terminated by the null character. If the user enters more characters than the edit_limit and the string is truncated, the null character is appended.


errtile

edit_box
Programmable Dialog Box Reference
image
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
errtile
errtile;

An error tile is a text tile that appears at the bottom of a dialog box. By default it is blank, but programs can display messages in it by setting the value of the tile whose key is "error". For example:

(set_tile "error" "You can only select one option")

The errtile tile is defined in the base.dcl file.


image

errtile
Programmable Dialog Box Reference
image_button
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
image
: image {
   action alignment aspect_ratio color
   fixed_height fixed_width height is_enabled
   is_tab_stop key mnemonic value width
}

An image is a rectangle in which a vector graphic picture is displayed. Images are used to display icons, linetypes, text fonts, and color patches in AutoCAD dialog boxes. See Creating Images for instructions on how to generate images for image tiles.

You must assign an image tile either an explicit width and height attribute, or one of those attributes plus an aspect_ratio.


image_button

image
Programmable Dialog Box Reference
list_box
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
image_button
: image_button {
   action alignment allow_accept aspect_ratio
   color fixed_height fixed_width height
   is_enabled is_tab_stop key mnemonic width
}

The image button tile is a button that displays a graphic image rather than a label.

When the user selects an image button, the program obtains the coordinates of the point that was selected. This is useful if you want to display a miniature drawing and assign different meanings to selecting different regions in it.

See Creating Images for instructions on how to generate images for image buttons.

You must assign an image button either an explicit width and height attribute, or one of those attributes plus an aspect_ratio.


list_box

image_button
Programmable Dialog Box Reference
ok_only
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
list_box
: list_box {
   action alignment allow_accept fixed_height
   fixed_width height is_enabled is_tab_stop
   key label list mnemonic multiple_select tabs
   value width
}

A list box contains a list of text strings, arranged in rows. Usually the list is of variable length, but list boxes can be used for fixed-length lists when a different kind of tile, such as a set of radio buttons, takes up too much space in the dialog box. When users select a row, it is highlighted. A list box can contain more rows than can fit in the box, so a scroll bar always appears to the right of the list box. (The scroll bar is enabled only if the list has more items than can appear at once.) By dragging the scroll bar cursor or clicking on its arrows, users can scroll through the list box items. Some applications may allow users to select multiple rows.

See List Boxes and Pop-Up Lists for instructions on how to manage lists for list boxes and pop-up lists.

NoteThe list_list tile is limited to 32,768 entries with the first element being an index of 0 and the last being 32,767. Once the limit is reached, the value of any entry that has an index greater than 32,767 is not accurately reported.
label

Text displayed above the list box.

value

A quoted string containing zero ("") or more integers, separated by spaces (no default). Each integer is a zero-based index that indicates a list item that is initially selected. If multiple_select is false, value cannot contain more than one integer.

If the value string is empty (""), then no items in the list are initially selected. In this case, you don't need to specify the value attribute at all.


ok_only

list_box
Programmable Dialog Box Reference
ok_cancel
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
ok_only
ok_only;

The ok_only tile is a solitary OK button, such as the kind that alert boxes use. The key of the OK button is "accept".

The ok_only tile is defined in the base.dcl file.


ok_cancel

ok_only
Programmable Dialog Box Reference
ok_cancel_help
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
ok_cancel
ok_cancel;

The ok_cancel tile is a combination of the OK and Cancel buttons, and is the standard combination for dialog boxes that can originate changes to data. The key of the Cancel button is "cancel".

The ok_cancel tile is defined in the base.dcl file.


ok_cancel_help

ok_cancel
Programmable Dialog Box Reference
ok_cancel_help_errtile
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
ok_cancel_help
ok_cancel_help;

This tile is the ok_cancel cluster combined with the Help button. The key of the Help button is "help". Help buttons are recommended for the main dialog box of an application and for complex dialog boxes. The function that handles the Help button can display the standard AutoCAD Help dialog box by invoking the AutoLISP help function.

The ok_cancel_help tile is defined in the base.dcl file.


ok_cancel_help_errtile

ok_cancel_help
Programmable Dialog Box Reference
ok_cancel_help_info
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
ok_cancel_help_errtile
ok_cancel_help_errtile;

The ok_cancel_help_errtile tile provides a convenient way to specify the exit buttons and error tile all at once.

The ok_cancel_help_errtile tile is defined in the base.dcl file.


ok_cancel_help_info

ok_cancel_help_errtile
Programmable Dialog Box Reference
paragraph
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
ok_cancel_help_info
ok_cancel_help_info;

The ok_cancel_help_info tile does everything that the ok_cancel_help tile does, but it also includes an information button for displaying additional material. It might display the name of your application, the logo of your firm, the application's version number, how to obtain support, and so on. The key of the Info button is "info".

The ok_cancel_help_info tile is defined in the base.dcl file.


paragraph

ok_cancel_help_info
Programmable Dialog Box Reference
popup_list
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
paragraph
: paragraph {
}

A paragraph is a cluster of text_part or concatenation tiles that are arranged vertically. You can construct paragraphs of running text either statically or at runtime. There is a margin around the paragraph as a whole.

The paragraph tile is defined in the base.dcl file.

The illustration above was generated with the following DCL:

: paragraph
{
  : concatenation
  {
    : text_part
    {
      label = "One";
    }
    : text_part
    {
      label = "good turn";
    }
  }
  : text_part {
    label = "Deserves another";
  }
}


popup_list

paragraph
Programmable Dialog Box Reference
radio_button
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
popup_list
: popup_list {
   action alignment edit_width fixed_height
   fixed_width height is_enabled is_tab_stop
   key label list mnemonic tabs value width
}

A pop-up list, or simply pop-up, is functionally equivalent to a list box. When a dialog box is first displayed, the pop-up is in a collapsed state and looks like a button except for the downward-pointing arrow on the right. When the user selects the text or the arrow, the list pops up and displays more selections. A pop-up list has a scroll bar on the right that works like the scroll bar of a list box. When a pop-up list is collapsed, the current selection appears in its display field. Pop-up lists do not allow multiple selection.

See List Boxes and Pop-Up Lists for instructions on how to manage lists for list boxes and pop-up lists.

NoteThe popup_list tile is limited to 32,768 entries with the first element being an index of 0 and the last being 32,767. Once the limit is reached, the value of any entry that has an index greater than 32,767 is not accurately reported.
label

Appears as a title to the left of the pop-up list. If specified, the label is left justified within the width of the popup_list tile.

edit_width

Specifies the width of the text portion of the list in character-width units. It doesn't include the optional label on the left or the pop-up arrow (or scroll bar) on the right. If edit_width isn't specified or is zero, and the width of the tile isn't fixed, the box expands to fill the available space. Possible value is an integer or a real number. If edit_width is nonzero, then the box is right-justified within the space occupied by the tile. If it is necessary to stretch the tile for layout purposes, the PDB feature inserts white space between the label and the edit portion of the box.

value

A quoted string containing an integer (default: "0"). The integer is a zero-based index that indicates the currently selected item in the list (the one that is displayed when the list isn't popped up).


radio_button

popup_list
Programmable Dialog Box Reference
radio_column
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
radio_button
: radio_button {
   action alignment fixed_height fixed_width
   height is_enabled is_tab_stop key label
   mnemonic value width
}

A radio button is one of a group of buttons composing a radio column or radio row. These work like the buttons on a car radio: only one can be selected at a time, and when one is pressed, any other button in the column (or row) that is on is turned off. An optional label appears to the right of the radio button. The PDB feature reports an error if you attempt to place a radio button outside a radio column or radio row.

label

The text displayed to the right of the radio button.

value

A quoted string (no default). If the value is "1", the radio_button is on; if it is "0", the radio_button is off; all other values are equivalent to "0".

If by some chance more than one radio_button in a radio cluster has value = "1", only the last one is turned on. (This can happen in a DCL file. Once the dialog box starts, the PDB feature manages radio buttons and ensures that only one per cluster is turned on at a time.)


radio_column

radio_button
Programmable Dialog Box Reference
radio_row
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
radio_column
: radio_column {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

A radio column contains radio button tiles, only one of which can be selected at a time. Radio columns present the user with a fixed set of mutually exclusive choices. Radio columns, unlike ordinary columns, can be assigned an action.

value

A quoted string containing the key of the currently selected radio button (the one whose value is "1").


radio_row

radio_column
Programmable Dialog Box Reference
row
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
radio_row
: radio_row {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

A radio row, like a radio column, contains radio button tiles, only one of which can be selected at a time. Radio rows can be assigned an action.

value

A quoted string containing the key of the currently selected radio button (the one whose value is "1").

NoteRadio rows are not as easy to use as radio columns, because the mouse has to travel farther. Use radio rows only if they specify two to four options, or if the labels are short.


row

radio_row
Programmable Dialog Box Reference
slider
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
row
: row {
   alignment children_alignment
   children_fixed_height children_fixed_width
   fixed_height fixed_width height label width
}

Tiles in a row are laid out horizontally in the order in which they appear in the DCL file. A row can contain any kind of tile.

A row without a box has no additional attributes beyond the standard layout attributes.


slider

row
Programmable Dialog Box Reference
text
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
slider
: slider {
   action alignment big_increment fixed_height
   fixed_width height key label layout
   max_value min_value mnemonic small_increment
   value width
}

A slider obtains a numeric value. The user can drag the slider's indicator to the left or right (or up or down) to obtain a value whose meaning depends on the application. This value is returned as a string containing a signed integer within a specified range (the integer is a 16-bit value, so the maximum range is -32,768 to 32,767). The application can scale this value as required.

value

A quoted string that contains the current (integer) value of the slider (default: min_value).


text

slider
Programmable Dialog Box Reference
text_part
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
text
: text {
   alignment fixed_height fixed_width height
   is_bold key label value width
}

A text tile displays a text string for titling or informational purposes.

Because most tiles have their own label attribute for titling purposes, you don't always need to use text tiles. But a text tile that you usually keep blank is a useful way to display feedback about user actions, error messages, or warnings.

Alert boxes and error tiles are discussed in Dialog Box Exit Buttons and Error Tiles and DCL Error Handling.

If you intend the message to be static, specify it in the label attribute and don't specify a width or value. If you intend the message to change at run-time, specify it in the value attribute and assign a width long enough to contain any strings that you plan to assign the value. Once the dialog box is laid out, the size of its tiles can't change, so if you use set_tile to assign a string longer than the width, the displayed text is truncated.

label

The displayed text. When a text tile is laid out, its width is the larger of either its width attribute, if that is specified in the DCL, or the width required by its label attribute, if specified. At least one of these attributes must be specified.

value

Like label, the value attribute specifies a string to display in the text tile. However, it has no effect on the tile's layout.


text_part

text
Programmable Dialog Box Reference
toggle
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
text_part
: text_part {
   label
}

A text part is a text tile that is part of a larger piece of text. The margins of a text_part are suppressed, so it can be combined with other text_parts into a concatenation or paragraph tile.

The text_part tile is defined in the base.dcl file. Seeparagraph for an example that uses text_part.


toggle

text_part
Programmable Dialog Box Reference
spacer
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
toggle
: toggle {
   action alignment fixed_height fixed_width
   height is_enabled is_tab_stop label width
}

A toggle controls a Boolean value ("0" or "1"). A toggle appears as a small box with an optional label to the right of the box. A check mark or X appears (or disappears) when the user selects the box. Toggles enable the user to view or change the state of on/off options. Toggles are also known as check boxes.

label

The text displayed to the right of the toggle box.

value

A quoted string containing an integer (default: "0") and specifying the initial state of the toggle. If the string is "0", the toggle box is blank (without a check mark). If it is "1", the box contains a check mark (or an X).


spacer

toggle
Programmable Dialog Box Reference
spacer_0
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
spacer
: spacer {
   alignment fixed_height fixed_width
   height width
}

A spacer is a blank tile. It is used only for layout purposes to affect the size and layout of adjacent tiles. To ensure consistency with other dialog boxes, use spacer tiles only in special cases, because the PDB feature handles spacing automatically. See Adjusting the Layout of Dialog Boxes.

The spacer tile has no additional attributes beyond the standard layout attributes.


spacer_0

spacer
Programmable Dialog Box Reference
spacer_1
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
spacer_0
spacer_0;

A spacer_0, demonstrated in the following figure, is a spacer that normally has no width. However, it indicates a point in a tile group where you want space to be inserted, if the group has to be stretched during layout. If the spacer_0 tiles in a group are assigned a positive width, all of them are assigned an equal share of the spacing.

The spacer_0 tile is defined in the base.dcl file.


spacer_1

spacer_0
Programmable Dialog Box Reference
Programmable Dialog Box Function Synopsis
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
spacer_1
spacer_1;

The spacer_1 tile, demonstrated in the following figure, is a spacer whose width and height both equal one. It is used for the smallest kind of spacer that will still be obvious to the user.

The spacer_1 tile is defined in the base.dcl file.


Programmable Dialog Box Function Synopsis

spacer_1
Programmable Dialog Box Reference
Dialog Box Opening and Closing Functions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference >
Programmable Dialog Box Function Synopsis

The programmable dialog box functions perform dialog box opening and closing, tile and attribute handling, list box and pop-up list handling, image tile handling, and application-specific data handling. This section lists each PDB function available in Visual LISP, grouping them by the type of task each performs. For detailed information on these functions, see the AutoLISP Reference.

Topics in this section

  • Dialog Box Opening and Closing Functions
  • Tile- and Attribute-Handling Functions
  • List Box and Pop-Up List-Handling Functions
  • Image Tile-Handling Functions
  • Application-Specific Data-Handling Function


Dialog Box Opening and Closing Functions

Programmable Dialog Box Function Synopsis
Programmable Dialog Box Function Synopsis
Tile- and Attribute-Handling Functions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Programmable Dialog Box Function Synopsis >
Dialog Box Opening and Closing Functions

The following table provides summary descriptions of the DCL opening and closing functions.

Dialog box opening and closing functions
Function name | Description
(done_dialog[status]) | Terminates a dialog box
(load_dialogdclfile) | Loads a DCL file
(new_dialogdlgname dcl_id [action [screen-pt]]) | Begins a new dialog box and displays it, and can also specify a default action
(start_dialog) | Displays a dialog box and begins accepting user input
(term_dialog) | Terminates all current dialog boxes as if the user cancels each of them
(unload_dialogdcl_id) | Unloads a DCL file


Tile- and Attribute-Handling Functions

Dialog Box Opening and Closing Functions
Programmable Dialog Box Function Synopsis
List Box and Pop-Up List-Handling Functions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Programmable Dialog Box Function Synopsis >
Tile- and Attribute-Handling Functions

The following table provides summary descriptions of the DCL tile- and attribute-handling functions.

Tile- and attribute-handling functions
Function name | Description
(action_tilekey action-expression) | Assigns an action to evaluate when the user selects the specified tile in a dialog box
(get_attrkey attribute) | Retrieves the DCL value of a dialog box attribute
(get_tilekey) | Retrieves the current runtime value of a dialog box tile
(mode_tilekey mode) | Sets the mode of a dialog box tile
(set_tilekey value) | Sets the value of a dialog box tile


List Box and Pop-Up List-Handling Functions

Tile- and Attribute-Handling Functions
Programmable Dialog Box Function Synopsis
Image Tile-Handling Functions
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Programmable Dialog Box Function Synopsis >
List Box and Pop-Up List-Handling Functions

The following table provides summary descriptions of the DCL list box and pop-up list-handling functions.

List box and pop-up list-handling functions
Function name | Description
(add_liststring) | Adds or modifies a string in the currently active dialog box list
(end_list) | Ends processing of the currently active dialog box list
(start_listkey [operation [index]]) | Starts the processing of a list in the list box or in the pop-up list dialog box tile


Image Tile-Handling Functions

List Box and Pop-Up List-Handling Functions
Programmable Dialog Box Function Synopsis
Application-Specific Data-Handling Function
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Programmable Dialog Box Function Synopsis >
Image Tile-Handling Functions

The following table provides summary descriptions of the DCL image tile-handling functions.

Image tile-handling functions
Function name | Description
(dimx_tilekey) and (dimy_tilekey) | Retrieves the dimensions of a tile in dialog box units
(end_image) | Ends creation of the currently active dialog box image
(fill_imagex1 y1 wid hgt color) | Draws a filled rectangle in the currently active dialog box image tile
(slide_imagex1 y1 wid hgt sldname) | Displays an AutoCAD slide in the currently active dialog box image tile
(start_imagekey) | Starts the creation of an image in the dialog box tile
(vector_imagex1 y1 x2 y2 color) | Draws a vector in the currently active dialog box image


Application-Specific Data-Handling Function

Image Tile-Handling Functions
Programmable Dialog Box Function Synopsis
Appendixes
AutoLISP Developer's Guide > Working with Programmable Dialog Boxes > Programmable Dialog Box Reference > Programmable Dialog Box Function Synopsis >
Application-Specific Data-Handling Function

The following table provides a summary description of the DCL application-specific data-handling function.

Application-specific data-handling function
Function name | Description
(client_data_tilekey clientdata) | Associates application-managed data with a dialog box tile


Appendixes

Application-Specific Data-Handling Function
AutoLISP Function Synopsis
AutoLISP Developer's Guide >
Appendixes

Topics in this section

  • AutoLISP Function Synopsis

    Functions are categorized and described.

  • Visual LISP Environment and Formatting Options

    Color-coding options, diagnostic options, and page layout options are described.

  • AutoLISP Error Codes

    The error codes generated by AutoLISP are described.


AutoLISP Function Synopsis

Appendixes
Appendixes
Category Summary
AutoLISP Developer's Guide > Appendixes >
AutoLISP Function Synopsis

Functions are categorized and described.

To find a function without knowing its name, use the listings in this appendix. The AutoLISP® functions in this synopsis are organized into functional groups, and listed alphabetically within each function group. Each function is briefly described by its signature and a single sentence indicating the function's purpose.

Topics in this section

  • Category Summary
  • Basic Functions
  • Utility Functions
  • Selection Set, Object, and Symbol Table Functions
  • Memory Management Functions
  • Visual LISP Extensions to AutoLISP
  • Reactor Functions
  • VLX Namespace Functions
  • Namespace Communication Functions
  • Windows Registry Functions


Category Summary

AutoLISP Function Synopsis
AutoLISP Function Synopsis
Basic Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Category Summary

Functions in this synopsis are organized into the following categories:

  • Basic: Application-handling, arithmetic, equality and conditional, error-handling, function-handling, list manipulation, string-handling, and symbol-handling functions
  • Utility: Conversion, device access, display control, file-handling, geometric, query and command, and user input functions
  • Selection Set, Object, and Symbol Table: Extended data-handling, object-handling, selection set manipulation, and symbol table-handling functions
  • Memory Management
  • Visual LISP Extensions to AutoLISP: Collection manipulation, curve measurement, data conversion, dictionary-handling, object-handling, and property-handling functions
  • Reactor
  • VLX Namespace: Function exposure, document namespace variable access, and error-handling functions
  • Namespace Communication: Blackboard-addressing and multi-document loading functions
  • Windows Registry Handling

Note that programmable dialog box functions are listed in the Programmable Dialog Box Function Synopsis section of this manual.

Functions are grouped by data type and by the action they perform. Detailed information on each Visual LISP® function is provided in the alphabetical listings in the AutoLISP Reference.

Note that any functions not described here or in other parts of the documentation are not officially supported and are subject to change in future releases.

Basic Functions
Application-Handling Functions | Application-Handling Functions
Arithmetic Functions | Arithmetic Functions
Equality and Conditional Functions | Equality and Conditional Functions
Error-Handling Functions | Error-Handling Functions
Function-Handling Functions | Function-Handling Functions
List Manipulation Functions | List Manipulation Functions
String-Handling Functions | String-Handling Functions
Symbol-Handling Functions | Symbol-Handling Functions
Utility Functions
Conversion Functions | Conversion Functions
Device Access Functions | Device Access Functions
Display Control Functions | Display Control Functions
File-Handling Functions | File-Handling Functions
Geometric Functions | Geometric Functions
Query and Command Functions | Query and Command Functions
User Input Functions | User Input Functions
Selection Set, Object, and Symbol Table Functions
Extended Data-Handling Functions | Extended Data-Handling Functions
Object-Handling Functions | Object-Handling Functions
Selection Set Manipulation Functions | Selection Set Manipulation Functions
Symbol Table and Dictionary-Handling Functions | Symbol Table and Dictionary-Handling Functions
Memory Management Functions | Memory Management Functions
Visual LISP AutoLISP Extensions
ActiveX Collection Manipulation Functions | ActiveX Collection Manipulation Functions
ActiveX Data Conversion Functions | ActiveX Data Conversion Functions
ActiveX Method Invocation Functions | ActiveX Method Invocation Functions
ActiveX Object-Handling Functions | ActiveX Object-Handling Functions
ActiveX Property-Handling Functions | ActiveX Property-Handling Functions
Curve Measurement Functions | Curve Measurement Functions
Dictionary Functions | Dictionary Functions
Functions for Handling Drawing Objects | Functions for Handling Drawing Objects
Reactor Functions | Reactor Functions
VLX Namespace Functions | VLX Namespace Functions
Namespace Communication Functions | Namespace Communication Functions
Windows Registry Functions | Windows Registry Functions


Basic Functions

Category Summary
AutoLISP Function Synopsis
Application-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Basic Functions

The basic functions consist of the arithmetic, string-handling, equality and conditional, list manipulation, symbol-handling, function-handling, error-handling, and application-handling functions.

Topics in this section

  • Application-Handling Functions
  • Arithmetic Functions
  • Equality and Conditional Functions
  • Error-Handling Functions
  • Function-Handling Functions
  • List Manipulation Functions
  • String-Handling Functions
  • Symbol-Handling Functions


Application-Handling Functions

Basic Functions
Basic Functions
Arithmetic Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
Application-Handling Functions

The following table provides summary descriptions of the AutoLISP application-handling functions.

Application-handling functions

Function

Description

( arx)

Returns a list of the currently loaded ObjectARX applications

( arxload application [onfailure])

Loads an ObjectARX application

( arxunload application [onfailure])

Unloads an ObjectARX application

( autoarxload filename cmdlist)

Predefines command names to load an associated ObjectARX file

( autoload filename cmdlist)

Predefines command names to load an associated AutoLISP file

( initdia[dialogflag])

Forces the display of the next command's dialog box

( load filename [onfailure])

Evaluates the AutoLISP expressions in a file

( startapp appcmd file)

Starts a Windows application

( vl-load-all filename)

Loads a file into all open AutoCAD documents

( vl-vbaload “filename”)

Loads a VBA project

( vl-vbarun “macroname”)

Runs a VBA macro

( vlax-add-cmd “global-name”

'func-sym [“local-name”

cmd-flags])

Adds commands to the AutoCAD built-in command set

NoteVLISP extension: requires vl-load-com


Arithmetic Functions

Application-Handling Functions
Basic Functions
Equality and Conditional Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
Arithmetic Functions

The following table provides summary descriptions of the AutoLISP arithmetic functions.

Arithmetic functions

Function

Description

( + (add) [numbernumber] ...)

Returns the sum of all numbers

( - (subtract) [number number] ...)

Subtracts the second and following numbers from the first and returns the difference

( * (multiply)[number number] ...)

Returns the product of all numbers

( / (divide)[number number] ...)

Divides the first number by the product of the remaining numbers and returns the quotient

( ~ (bitwise NOT)int)

Returns the bitwise NOT (1's complement) of the argument

( 1+ (increment)number)

Returns the argument increased by 1 (incremented)

( 1- (decrement)number)

Returns the argument reduced by 1 (decremented)

( abs number)

Returns the absolute value of the argument

( atan num1 [num2])

Returns the arctangent of a number in radians

( cos ang)

Returns the cosine of an angle expressed in radians

( exp number)

Returns the constant e (a real) raised to a specified power (the natural antilog)

( expt base power)

Returns a number raised to a specified power

( fix number)

Returns the conversion of a real into the nearest smaller integer

( float number)

Returns the conversion of a number into a real

( gcd int1 int2)

Returns the greatest common denominator of two integers

( log number)

Returns the natural log of a number as a real

( logand [int int ...])

Returns the result of the logical bitwise AND of a list of integers

( logior [intint ...])

Returns the result of the logical bitwise inclusive OR of a list of integers

( lsh [intnumbits])

Returns the logical bitwise shift of an integer by a specified number of bits

( max [number number ...])

Returns the largest of the numbers given

( min [number number ...])

Returns the smallest of the numbers given

( minusp number)

Verifies that a number is negative

( rem [num1 num2 ...])

Divides the first number by the second, and returns the remainder

( sin ang)

Returns the sine of an angle as a real expressed in radians

( sqrt number)

Returns the square root of a number as a real

( zerop number)

Verifies that a number evaluates to zero


Equality and Conditional Functions

Arithmetic Functions
Basic Functions
Error-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
Equality and Conditional Functions

The following table provides summary descriptions of the AutoLISP equality and conditional functions.

Equality and conditional functions

Function

Description

( = (equal to)numstr [numstr] ...)

Returns T if all arguments are numerically equal, and returns nil otherwise

( /= (not equal to)numstr [numstr] ...)

Returns T if the arguments are not numerically equal, and nil if the arguments are numerically equal

( < (less than)numstr [numstr] ...)

Returns T if each argument is numerically less than the argument to its right, and returns nil otherwise

( <= (less than or equal to)numstr [numstr] ...)

Returns T if each argument is numerically less than or equal to the argument to its right, and returns nil otherwise

( > (greater than)numstr [numstr] ...)

Returns T if each argument is numerically greater than the argument to its right, and returns nil otherwise

( >= (greater than or equal to)numstr [numstr] ...)

Returns T if each argument is numerically greater than or equal to the argument to its right, and returns nil otherwise

( and [expr ...])

Returns the logical AND of a list of expressions

( Boole func int1 [int2 ...])

Serves as a general bitwise Boolean function

( cond [(test result ...) ...])

Serves as the primary conditional function for AutoLISP

( eq expr1 expr2)

Determines whether two expressions are identical

( equal expr1 expr2 [fuzz])

Determines whether two expressions are equal

( if testexpr thenexpr [elseexpr])

Conditionally evaluates expressions

( or [expr ...])

Returns the logical OR of a list of expressions

( repeat int [expr ...])

Evaluates each expression a specified number of times, and returns the value of the last expression

( while testexpr [expr ...])

Evaluates a test expression, and if it is not nil, evaluates other expressions; repeats this process until the test expression evaluates to nil


Error-Handling Functions

Equality and Conditional Functions
Basic Functions
Function-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
Error-Handling Functions

The following table provides summary descriptions of the AutoLISP error-handling functions.

Error-handling functions

Function

Description

( alert string)

Displays an alert dialog box with the error or warning message passed as a string

( *error*string)

A user-definable error-handling function

( exit)

Forces the current application to quit

( quit)

Forces the current application to quit

( vl-catch-all-apply 'functionlist)

Passes a list of arguments to a specified function and traps any exceptions

( vl-catch-all-error-message

error-obj)

Returns a string from an error object

( vl-catch-all-error-p arg)

Determines whether an argument is an error object returned from vl-catch-all-apply


Function-Handling Functions

Error-Handling Functions
Basic Functions
List Manipulation Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
Function-Handling Functions

The following table provides summary descriptions of the AutoLISP function-handling functions.

Function-handling functions

Function

Description

( apply function lst)

Passes a list of arguments to a specified function

( defun sym ([arguments]

[/variables...]) expr ...)

Defines a function

( defun-q sym ([arguments]

[/variables...]) expr ...)

Defines a function as a list (intended for backward-compatibility only)

( defun-q-list-ref 'function)

Displays the list structure of a function defined with defun-q

( defun-q-list-set'sym list)

Defines a function as a list (intended for backward-compatibility only)

( eval expr)

Returns the result of evaluating an AutoLISP expression

( lambda arguments expr ...)

Defines an anonymous function

( progn[expr] ...)

Evaluates each expression sequentially, and returns the value of the last expression

( trace function ...)

Aids in AutoLISP debugging

( untrace function ...)

Clears the trace flag for the specified functions


List Manipulation Functions

Function-Handling Functions
Basic Functions
String-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
List Manipulation Functions

The following table provides summary descriptions of the AutoLISP list manipulation functions.

List manipulation functions

Function

Description

( acad_strlsort lst)

Sorts a list of strings by alphabetical order

( append lst ...)

Takes any number of lists and runs them together as one list

( assoc item alist)

Searches an association list for an element and returns that association list entry

( car lst)

Returns the first element of a list

( cdr lst)

Returns the specified list, except for the first element of the list

( cons new-first-element lst)

The basic list constructor

( foreach name lst [expr ...])

Evaluates expressions for all members of a list

( last lst)

Returns the last element in a list

( length lst)

Returns an integer indicating the number of elements in a list

( list [expr ...])

Takes any number of expressions and combines them into one list

( listp item)

Verifies that an item is a list

( mapcar functionlist1 ... listn)

Returns a list of the result of executing a function with the individual elements of a list or lists supplied as arguments to the function

( member expr lst)

Searches a list for an occurrence of an expression and returns the remainder of the list, starting with the first occurrence of the expression

( nth n lst)

Returns the nth element of a list

( reverse lst)

Returns a list with its elements reversed

( subst newitem olditem lst)

Searches a list for an old item and returns a copy of the list with a new item substituted in place of every occurrence of the old item

( vl-consp list-variable)

Determines whether or not a list is nil

( vl-every predicate-functionlist [more-lists]...)

Checks whether the predicate is true for every element combination

( vl-list*object [more-objects]...)

Constructs and returns a list

( vl-list->string char-codes-list)

Combines the characters associated with a list of integers into a string

( vl-list-length list-or-cons-object)

Calculates list length of a true list

( vl-member-if predicate-function list)

Determines whether the predicate is true for one of the list members

( vl-member-if-not predicate-function list)

Determines whether the predicate is nil for one of the list members

( vl-position symbol list)

Returns the index of the specified list item

( vl-remove element-to-remove

list)

Removes elements from a list

( vl-remove-if predicate-functionlist)

Returns all elements of the supplied list that fail the test function

( vl-remove-if-not predicate-functionlist)

Returns all elements of the supplied list that pass the test function

( vl-some predicate-functionlist [more-lists]...)

Checks whether the predicate is not nil for one element combination

( vl-sort list less?-function)

Sorts the elements in a list according to a given compare function

( vl-sort-i list less?-function)

Sorts the elements in a list according to a given compare function, and returns the element index numbers

( vl-string->list string)

Converts a string into a list of character codes


String-Handling Functions

List Manipulation Functions
Basic Functions
Symbol-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
String-Handling Functions

The following table provides summary descriptions of the AutoLISP string-handling functions.

String-handling functions

Function

Description

( read[string])

Returns the first list or atom obtained from a string

( strcase string [which])

Returns a string where all alphabetic characters have been converted to uppercase or lowercase

( strcat [string1 [string2] ...)

Returns a string that is the concatenation of multiple strings

( strlen [string] ...)

Returns an integer that is the number of characters in a string

( substr string start [length])

Returns a substring of a string

( vl-prin1-to-string object)

Returns the string representation of any LISP object as if it were output by the prin1 function

( vl-princ-to-string object)

Returns the string representation of any LISP object as if it were output by the princ function

( vl-string->list string)

Converts a string into a list of character codes

( vl-string-elt string position)

Returns the ASCII representation of the character at a specified position in a string

( vl-string-left-trim character-setstring)

Removes the specified characters from the beginning of a string

( vl-string-mismatch str1str2

[pos1pos2ignore-case-p])

Returns the length of the longest common prefix for two strings, starting at specified positions

( vl-string-position char-codestr

[start-pos [from-end-p]])

Looks for a character with the specified ASCII code in a string

( vl-string-right-trim

character-setstring)

Removes the specified characters from the end of a string

( vl-string-search patternstring [start-pos])

Searches for the specified pattern in a string

( vl-string-subst new-strpatternstring

[start-pos])

Substitutes one string for another, within a string

( vl-string-translate

source-setdest-setstr)

Replaces characters in a string with a specified set of characters

( vl-string-trim char-setstr)

Removes the specified characters from the beginning and end of a string

( wcmatch string pattern)

Performs a wild-card pattern match on a string


Symbol-Handling Functions

String-Handling Functions
Basic Functions
Utility Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Basic Functions >
Symbol-Handling Functions

The following table provides summary descriptions of the AutoLISP symbol-handling functions.

Symbol-handling functions

Function

Description

( atom item)

Verifies that an item is an atom

( atoms-family format [symlist])

Returns a list of the currently defined symbols

( boundp sym)

Verifies whether a value is bound to a symbol

( not item)

Verifies that an item evaluates to nil

( null item)

Verifies that an item is bound to nil

( numberp item)

Verifies that an item is a real or an integer

( quote expr)

Returns an expression without evaluating it

( set sym expr)

Sets the value of a quoted symbol name to an expression

( setq sym1 expr1

[sym2 expr2] ...)

Sets the value of a symbol or symbols to associated expressions

( type item)

Returns the type of a specified item

( vl-symbol-name symbol)

Returns a string containing the name of a symbol

( vl-symbol-value symbol)

Returns the current value bound to a symbol

( vl-symbolp object)

Identifies whether or not a specified object is a symbol


Utility Functions

Symbol-Handling Functions
AutoLISP Function Synopsis
Conversion Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Utility Functions

The utility functions consist of query and command, display control, user input, geometric, conversion, file-handling, and device access functions.

Topics in this section

  • Conversion Functions
  • Device Access Functions
  • Display Control Functions
  • File-Handling Functions
  • Geometric Functions
  • Query and Command Functions
  • User Input Functions


Conversion Functions

Utility Functions
Utility Functions
Device Access Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
Conversion Functions

The following table provides summary descriptions of the AutoLISP conversion functions.

Conversion functions

Function

Description

( angtof string [mode])

Converts a string representing an angle into a real (floating-point) value in radians

( angtos angle [mode [precision]])

Converts an angular value in radians into a string

( ascii string)

Returns the conversion of the first character of a string into its ASCII character code (an integer)

( atof string)

Returns the conversion of a string into a real

( atoi string)

Returns the conversion of a string into an integer

( chr integer)

Returns the conversion of an integer representing an ASCII character code into a single-character string

( cvunit value from to)

Converts a value from one unit of measurement to another

( distof string [mode])

Converts a string that represents a real (floating-point) value into a real value

( itoa int)

Returns the conversion of an integer into a string

( rtos number [mode [precision]])

Converts a number into a string

( trans pt from to [disp])

Translates a point (or a displacement) from one coordinate system to another


Device Access Functions

Conversion Functions
Utility Functions
Display Control Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
Device Access Functions

The following table provides summary descriptions of the AutoLISP device access functions.

Device access functions

Function

Description

( grread [track] [allkeys [curtype]])

Reads values from any of the AutoCAD input devices

( tablet code [row1 row2 row3 direction])

Retrieves and sets digitizer (tablet) calibrations


Display Control Functions

Device Access Functions
Utility Functions
File-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
Display Control Functions

The following table provides summary descriptions of the AutoLISP display control functions.

Display control functions

Function

Description

( graphscr)

Displays the AutoCAD graphics screen

( grdraw from to color [highlight])

Draws a vector between two points, in the current viewport

( grtext[box text [highlight]])

Writes text to the status line or to screen menu areas

( grvecs vlist [trans])

Draws multiple vectors on the graphics screen

( menucmd string)

Issues menu commands, or sets and retrieves menu item status

( menugroup groupname)

Verifies that a menu group is loaded

( prin1[expr [file-desc]])

Prints an expression to the command line or writes an expression to an open file

( princ [expr [file-desc]])

Prints an expression to the command line, or writes an expression to an open file

( print[expr [file-desc]])

Prints an expression to the command line, or writes an expression to an open file

( prompt msg)

Displays a string on your screen's prompt area

( redraw[ename [mode]])

Redraws the current viewport or a specified object (entity) in the current viewport

( terpri)

Prints a newline to the Command line

( textpage)

Switches from the graphics screen to the text screen

( textscr)

Switches from the graphics screen to the text screen (like the AutoCAD Flip Screen function key)

( vports)

Returns a list of viewport descriptors for the current viewport configuration


File-Handling Functions

Display Control Functions
Utility Functions
Geometric Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
File-Handling Functions

The following table provides summary descriptions of the AutoLISP file-handling functions.

File-handling functions

Function

Description

( close file-desc)

Closes an open file

( findfile filename)

Searches the AutoCAD library path for the specified file

( open filename mode)

Opens a file for access by the AutoLISP I/O functions

( read-char[file-desc])

Returns the decimal ASCII code representing the character read from the keyboard input buffer or from an open file

( read-line[file-desc])

Reads a string from the keyboard or from an open file

( vl-directory-files [directory

patterndirectories])

Lists all files in a given directory

( vl-file-copy "source-filename"

"destination-filename" [append?])

Copies or appends the contents of one file to another file

( vl-file-delete "filename")

Deletes a file

( vl-file-directory-p "filename")

Determines if a file name refers to a directory

( vl-file-rename "old-filename"

"new-filename")

Renames a file

( vl-file-size "filename")

Determines the size of a file, in bytes

( vl-file-systime "filename")

Returns last modification time of the specified file

( vl-filename-base "filename")

Returns the name of a file, after stripping out the directory path and extension

( vl-filename-directory

"filename")

Returns the directory path of a file, after stripping out the name and extension

( vl-filename-extension

"filename")

Returns the extension from a file name, after stripping out the rest of the name

( vl-filename-mktemp

["pattern" "directory" "extension"])

Calculates a unique file name to be used for a temporary file

( write-char num [file-desc])

Writes one character to the screen or to an open file

( write-line string [file-desc])

Writes a string to the screen or to an open file


Geometric Functions

File-Handling Functions
Utility Functions
Query and Command Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
Geometric Functions

The following table provides summary descriptions of the AutoLISP geometric functions.

Geometric functions

Function

Description

( angle pt1 pt2)

Returns an angle in radians of a line defined by two endpoints

( distance pt1 pt2)

Returns the 3D distance between two points

( inters pt1 pt2 pt3 pt4 [onseg])

Finds the intersection of two lines

( osnap pt mode)

Returns a 3D point that is the result of applying an Object Snap mode to a specified point

( polar pt ang dist)

Returns the UCS 3D point at a specified angle and distance from a point

( textbox elist)

Measures a specified text object, and returns the diagonal coordinates of a box that encloses the text


Query and Command Functions

Geometric Functions
Utility Functions
User Input Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
Query and Command Functions

The following table provides summary descriptions of the AutoLISP query and command functions.

Query and command functions

Function

Description

( acad_colordlg colornum [flag])

Displays the standard AutoCAD Color Selection dialog box

( acad_helpdlg helpfile topic)

Invokes the Help facility (obsolete)

( command [arguments] ...)

Executes an AutoCAD command

( getcfg cfgname)

Retrieves application data from the AppData section of the acad*.cfg file

( getcname cname)

Retrieves the localized or English name of an AutoCAD command

( getenv "variable-name")

Returns the string value assigned to an environment variable

( getvar varname)

Retrieves the value of an AutoCAD system variable

( help[helpfile [topic

[command]]])

Invokes the Help facility

( setcfg cfgname cfgval)

Writes application data to the AppData section of the acad*.cfg file

( setenv "varname""value")

Sets an environment variable to a specified value

( setfunhelp "c:fname"

["helpfile" ["topic" ["command"]]])

Registers a user-defined command with the Help facility so the appropriate help file and topic are called when the user requests help on that command

( setvar varname value)

Sets an AutoCAD system variable to a specified value

( ver)

Returns a string that contains the current AutoLISP version number

( vl-cmdf [arguments] ...)

Executes an AutoCAD command after evaluating arguments

( vlax-add-cmd global-name

func-sym [local-name cmd-flags])

Adds commands to a group

NoteVLISP extension: requires vl-load-com

( vlax-remove-cmd global-name)

Removes a single command or command group

NoteVLISP extension: requires vl-load-com


User Input Functions

Query and Command Functions
Utility Functions
Selection Set, Object, and Symbol Table Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Utility Functions >
User Input Functions

The following table provides summary descriptions of the AutoLISP user input functions.

User input functions

Function

Description

( entsel[msg])

Prompts the user to select a single object (entity) by specifying a point

( getangle[pt] [msg])

Pauses for user input of an angle, and returns that angle in radians

( getcorner pt [msg])

Pauses for user input of a rectangle's second corner

( getdist[pt] [msg])

Pauses for user input of a distance

( getfiled title default ext flags)

Prompts the user for a file name with the standard AutoCAD file dialog box, and returns that file name

( getint[msg])

Pauses for user input of an integer, and returns that integer

( getkword[msg])

Pauses for user input of a keyword, and returns that keyword

( getorient[pt] [msg])

Pauses for user input of an angle, and returns that angle in radians

( getpoint[pt] [msg])

Pauses for user input of a point, and returns that point

( getreal[msg])

Pauses for user input of a real number, and returns that real number

( getstring [cr][msg])

Pauses for user input of a string, and returns that string

( initget[bits] [string])

Establishes keywords for use by the next user input function call

( nentsel [msg])

Prompts the user to select an object (entity) by specifying a point, and provides access to the definition data contained within a complex object

( nentselp [msg] [pt])

Provides similar functionality to that of the nentsel function without the need for user input


Selection Set, Object, and Symbol Table Functions

User Input Functions
AutoLISP Function Synopsis
Extended Data-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Selection Set, Object, and Symbol Table Functions

The selection set, object, and symbol table functions consist of selection set manipulation, object-handling, extended data-handling, and symbol table-handling functions.

Topics in this section

  • Extended Data-Handling Functions
  • Object-Handling Functions
  • Selection Set Manipulation Functions
  • Symbol Table and Dictionary-Handling Functions


Extended Data-Handling Functions

Selection Set, Object, and Symbol Table Functions
Selection Set, Object, and Symbol Table Functions
Object-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Selection Set, Object, and Symbol Table Functions >
Extended Data-Handling Functions

The following table provides summary descriptions of the AutoLISP extended data-handling functions.

Extended data-handling functions

Function

Description

( regapp application)

Registers an application name with the current AutoCAD drawing in preparation for using extended object data

( xdroom ename)

Returns the amount of extended data (xdata) space that is available for an object (entity)

( xdsize lst)

Returns the size (in bytes) that a list occupies when it is linked to an object (entity) as extended data


Object-Handling Functions

Extended Data-Handling Functions
Selection Set, Object, and Symbol Table Functions
Selection Set Manipulation Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Selection Set, Object, and Symbol Table Functions >
Object-Handling Functions

The following table provides summary descriptions of the AutoLISP object-handling functions.

Object-handling functions

Function

Description

( entdel ename)

Deletes objects (entities) or restores previously deleted objects

( entget ename [applist])

Retrieves an object's definition data

( entlast)

Returns the name of the last nondeleted main object in the drawing

( entmake [elist])

Creates a new entity (graphical object) in the drawing

( entmakex [elist])

Makes a new object, gives it a handle and entity name (but does not assign an owner), and then returns the new entity name

( entmod elist)

Modifies the definition data of an object

( entnext[ename])

Returns the name of the next object in the drawing

( entupd ename)

Updates the screen image of an object

( handent handle)

Returns an object name based on its handle

( vlax-dump-object obj)

Lists an object's methods and properties

NoteVLISP extension: requires vl-load-com

( vlax-erased-p obj)

Determines whether an object was erased

NoteVLISP extension: requires vl-load-com

( vlax-get-acad-object)

Retrieves the top-level AutoCAD application object for the current AutoCAD session

NoteVLISP extension: requires vl-load-com

( vlax-method-applicable-p objmethod)

Determines whether an object supports a particular method

NoteVLISP extension: requires vl-load-com

( vlax-object-released-p obj)

Determines whether an object has been released

NoteVLISP extension: requires vl-load-com

( vlax-read-enabled-p obj)

Determines whether an object can be read

NoteVLISP extension: requires vl-load-com

( vlax-release-object obj)

Releases a drawing object

NoteVLISP extension: requires vl-load-com

( vlax-typeinfo-available-p obj)

Determines whether type library information is present for the specified type of object

NoteVLISP extension: requires vl-load-com

( vlax-write-enabled-p obj)

Determines whether an AutoCAD drawing object can be modified

NoteVLISP extension: requires vl-load-com


Selection Set Manipulation Functions

Object-Handling Functions
Selection Set, Object, and Symbol Table Functions
Symbol Table and Dictionary-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Selection Set, Object, and Symbol Table Functions >
Selection Set Manipulation Functions

The following table provides summary descriptions of the AutoLISP selection set manipulation functions.

Selection set manipulation functions

Function

Description

( ssadd[ename[ss]])

Adds an object (entity) to a selection set, or creates a new selection set

( ssdel enamess)

Deletes an object (entity) from a selection set

( ssget[mode] [pt1 [pt2]] [pt-list]

[filter-list])

Prompts the user to select objects (entities), and returns a selection set

( ssgetfirst)

Determines which objects are selected and gripped

( sslength ss)

Returns an integer containing the number of objects (entities) in a selection set

( ssmemb enamess)

Tests whether an object (entity) is a member of a selection set

( ssname ssindex)

Returns the object (entity) name of the indexed element of a selection set

( ssnamex ssindex)

Retrieves information about how a selection set was created

( sssetfirst gripset [pickset])

Sets which objects are selected and gripped


Symbol Table and Dictionary-Handling Functions

Selection Set Manipulation Functions
Selection Set, Object, and Symbol Table Functions
Memory Management Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Selection Set, Object, and Symbol Table Functions >
Symbol Table and Dictionary-Handling Functions

The following table provides summary descriptions of the AutoLISP symbol table and dictionary-handling functions.

Symbol table and dictionary-handling functions

Function

Description

( dictadd ename symbol newobj)

Adds a non-graphical object to the specified dictionary

( dictnext ename symbol [rewind])

Finds the next item in a dictionary

( dictremove ename symbol)

Removes an entry from the specified dictionary

( dictrename ename oldsym newsym)

Renames a dictionary entry

( dictsearch ename symbol [setnext])

Searches a dictionary for an item

( layoutlist)

Returns a list of all paper space layouts in the current drawing

( namedobjdict)

Returns the entity name of the current drawing's named object dictionary, which is the root of all non-graphical objects in the drawing

( setview view_description [vport_id])

Establishes a view for a specified viewport

( snvalid sym_name)

Checks the symbol table name for valid characters

( tblnext table-name [rewind])

Finds the next item in a symbol table

( tblobjname table-name symbol)

Returns the entity name of a specified symbol table entry

( tblsearch table-name symbol [setnext])

Searches a symbol table for a symbol name

( vlax-ldata-list dictkey)

Erases AutoLISP data from a drawing dictionary

NoteVLISP extension: requires vl-load-com

( vlax-ldata-get dictkey [default-data])

Retrieves AutoLISP data from a drawing dictionary

NoteVLISP extension: requires vl-load-com

( vlax-ldata-list dict)

Lists AutoLISP data in a drawing dictionary

NoteVLISP extension: requires vl-load-com

( vlax-ldata-put dictkeydata)

Stores AutoLISP data in a drawing dictionary

NoteVLISP extension: requires vl-load-com

( vlax-ldata-test data)

Determines whether data can be saved over a session boundary

NoteVLISP extension: requires vl-load-com


Memory Management Functions

Symbol Table and Dictionary-Handling Functions
AutoLISP Function Synopsis
Visual LISP Extensions to AutoLISP
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Memory Management Functions

The following table provides summary descriptions of the AutoLISP memory management functions.

Memory management functions

Function

Description

( alloc int)

Sets the segment size to a given number of nodes

( expand number)

Allocates node space by requesting a specified number of segments

( gc)

Forces a garbage collection, which frees up unused memory

( mem)

Displays the current state of memory in AutoLISP


Visual LISP Extensions to AutoLISP

Memory Management Functions
AutoLISP Function Synopsis
ActiveX Collection Manipulation Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Visual LISP Extensions to AutoLISP

The extended AutoLISP functions provided with VLISP consist of curve measurement, data conversion, object-handling, property-handling, collection manipulation, and dictionary-handling functions. The function names are prefixed with vlax-. These functions are in addition to the ActiveX® methods provided through vla-* functions.

NoteBefore you can use the AutoLISP extensions, you must issue the following command:

(vl-load-com)

The vl-load-com function also initializes ActiveX support for AutoLISP.

Topics in this section

  • ActiveX Collection Manipulation Functions
  • ActiveX Data Conversion Functions
  • ActiveX Method Invocation Functions
  • ActiveX Object-Handling Functions
  • ActiveX Property-Handling Functions
  • Curve Measurement Functions
  • Dictionary Functions
  • Functions for Handling Drawing Objects


ActiveX Collection Manipulation Functions

Visual LISP Extensions to AutoLISP
Visual LISP Extensions to AutoLISP
ActiveX Data Conversion Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
ActiveX Collection Manipulation Functions

The following table provides summary descriptions of the AutoLISP ActiveX collection manipulation functions.

Collection manipulation functions

Function

Description

( vlax-for symbolcollection

[expression1 [expression2 ...]])

Iterates through a collection of objects, evaluating each expression (VLISP Function)

( vlax-map-collection obj

function)

Applies a function to all objects in a collection


ActiveX Data Conversion Functions

ActiveX Collection Manipulation Functions
Visual LISP Extensions to AutoLISP
ActiveX Method Invocation Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
ActiveX Data Conversion Functions

The following table provides summary descriptions of the AutoLISP ActiveX data conversion functions.

Data conversion functions

Function

Description

( vlax-3D-point list)

Creates an ActiveX-compatible 3D point structure

( vlax-ename->vla-object

entname)

Transforms entity to VLA-object

( vlax-make-safearray type

'(l-bound . u-bound)

[ '(l-bound . u-bound)...)]

Creates a safearray

( vlax-make-variant valuetype)

Creates a variant data type

( vlax-safearray-fill var '

element-values)

Stores elements in a safearray

( vlax-safearray-get-dim var)

Returns the number of dimensions in a safearray object

( vlax-safearray-get-element varelement)

Returns an element from an array

( vlax-safearray-get-l-bound vardim)

Returns the lower boundary (starting index) of a dimension of an array

( vlax-safearray-get-u-bound vardim)

Returns the upper boundary (end index) of a dimension of an array

( vlax-safearray-put-element var

element value)

Adds or updates an element in an array

( vlax-safearray-type var)

Returns the data type of a safearray

( vlax-safearray->list var)

Returns the elements of a safearray in list form

( vlax-tmatrix list)

Returns a suitable representation for a 4 x 4 transformation matrix to be used in VLA methods

( vlax-variant-change-type vartype)

Returns the value of a variant after changing it from one data type to another

( vlax-variant-type var)

Returns the data type of a variant

( vlax-variant-value var)

Returns the value of a variant

( vlax-vla-object->ename obj)

Transforms a VLA-object to an AutoLISP entity


ActiveX Method Invocation Functions

ActiveX Data Conversion Functions
Visual LISP Extensions to AutoLISP
ActiveX Object-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
ActiveX Method Invocation Functions

The following table provides summary descriptions of the AutoLISP ActiveX method invocation functions.

Method invocation functions

Function

Description

( vlax-invoke-method objmethodlist)

Calls the specified method of an object

( vlax-method-applicable-p objmethod)

Determines if an object supports a particular method


ActiveX Object-Handling Functions

ActiveX Method Invocation Functions
Visual LISP Extensions to AutoLISP
ActiveX Property-Handling Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
ActiveX Object-Handling Functions

The following table provides summary descriptions of the AutoLISP ActiveX object-handling functions.

ActiveX Object-handling functions

Function

Description

( vlax-dump-object obj)

Lists an object's methods and properties

( vlax-erased-p obj)

Determines whether an object was erased

( vlax-get-acad-object)

Retrieves the top-level AutoCAD application object for the current AutoCAD session

( vlax-method-applicable-p objmethod)

Determines if an object supports a particular method

( vlax-object-released-p obj)

Determines if an object has been released

( vlax-read-enabled-p obj)

Determines whether an object can be read

( vlax-release-object obj)

Releases a graphical object

( vlax-typeinfo-available-p obj)

Determines whether type library information is present for the specified type of object

( vlax-write-enabled-p obj)

Determines whether an AutoCAD drawing object can be modified


ActiveX Property-Handling Functions

ActiveX Object-Handling Functions
Visual LISP Extensions to AutoLISP
Curve Measurement FunctionsAutoLISP:curve measurement functionsAutoLISP:Visual LISP extended functions:curve measurement functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
ActiveX Property-Handling Functions

The following table provides summary descriptions of the AutoLISP property-handling functions.

Property-handling functions

Function

Description

( vlax-get-property objproperty)

Low-level property get function. May be used for custom ActiveX object

( vlax-property-available-p

objprop [T])

Determines whether an object has a specified property

( vlax-put-property objpropertyarg)

Low-level property set function


Curve Measurement Functions

ActiveX Property-Handling Functions
Visual LISP Extensions to AutoLISP
Dictionary Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
Curve Measurement Functions

The following table provides summary descriptions of the AutoLISP curve measurement functions.

Curve measurement functions

Function

Description

( vlax-curve-getArea curve-obj)

Returns the area inside the curve

( vlax-curve-getDistAtParam

curve-objparam)

Returns the length of the curve's segment from the curve's beginning to the specified point

( vlax-curve-getDistAtPoint

curve-objpoint)

Returns the length of the curve's segment between the curve's start point and the specified point

( vlax-curve-getEndParam

curve-obj)

Returns the parameter of the endpoint of the curve

( vlax-curve-getEndPoint

curve-obj)

Returns the endpoint (in WCS coordinates) of the curve

( vlax-curve-getParamAtPoint

curve-objparam)

Returns the distance along the curve from the beginning of the curve to the location of the specified parameter

( vlax-curve-getParamAtPoint

curve-objpoint)

Returns the parameter of the curve at the point

( vlax-curve-getPointAtDist

curve-objdist)

Returns the point (in WCS coordinates) along a curve at the distance specified by the user

( vlax-curve-getPointAtParam

curve-objparam)

Determines the point on the curve that corresponds to the param parameter and returns the point

( vlax-curve-getStartParam

curve-obj)

Returns the start parameter on the curve

( vlax-curve-getStartPoint

curve-obj)

Returns the start point (in WCS coordinates) of the curve

( vlax-curve-isClosed

curve-obj)

Determines if the specified curve is closed (i.e., start point is same as endpoint)

( vlax-curve-isPeriodic curve-obj)

Determines if the specified curve has an infinite range in both directions and there is a period value dT, such that there is a point on curve at (u + dT) = point on curve (u), for any parameter u

( vlax-curve-isPlanar curve-obj)

Determines if there is a plane that contains the curve

( vlax-curve-getClosestPointTo

curve-obj givenPnt [extend])

Returns the point (in WCS coordinates) on a curve that is nearest to the specified point

( vlax-curve-getClosestPointToProjection curve-obj givenPnt normal [extend])

Returns the point (in WCS coordinates) on a curve that is nearest to the specified point

( vlax-curve-getFirstDeriv

curve-obj param)

Returns the first derivative (in WCS coordinates) of a curve at the specified location

( vlax-curve-getSecondDeriv curve-obj param)

Returns the second derivative (in WCS coordinates) of a curve at the specified location


Dictionary Functions

Curve Measurement FunctionsAutoLISP:curve measurement functionsAutoLISP:Visual LISP extended functions:curve measurement functions
Visual LISP Extensions to AutoLISP
Functions for Handling Drawing Objects
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
Dictionary Functions

The following table provides summary descriptions of the AutoLISP dictionary functions.

Dictionary functions

Function

Description

( vlax-ldata-delete dictkey)

Erases AutoLISP data from a drawing dictionary

( vlax-ldata-get dictkey

[default-data])

Retrieves AutoLISP data from a drawing dictionary

( vlax-ldata-list dict)

Lists AutoLISP data in a drawing dictionary

( vlax-ldata-put dictkeydata)

Stores AutoLISP data in a drawing dictionary

( vlax-ldata-test data)

Determines whether data can be saved over a session boundary


Functions for Handling Drawing Objects

Dictionary Functions
Visual LISP Extensions to AutoLISP
Reactor Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis > Visual LISP Extensions to AutoLISP >
Functions for Handling Drawing Objects

The following table provides summary descriptions of the AutoLISP functions for handling drawing objects.

Functions for handling drawing objects

Function

Description

( vlax-create-object “prog-id”)

Creates a new instance of an ActiveX object

( vlax-dump-object obj)

Lists an object's methods and properties

( vlax-erased-p obj)

Determines whether an object was erased

( vlax-get-acad-object)

Retrieves the top-level AutoCAD application object for the current AutoCAD session

( vlax-get-object “prog-id”)

Returns a running instance of an ActiveX object

( vlax-get-or-create-object

“prog-id”)

Returns a running instance of an ActiveX object, if one exists, otherwise starts a new instance of the object

( vlax-import-type-library

:tlb-filename filename

[ :methods-prefix mprefix

:properties-prefix pprefix

:constants-prefix cprefix])

Imports information from a type library

( vlax-method-applicable-p

objmethod)

Determines whether an object supports a particular method

( vlax-object-released-p obj)

Determines whether an object has been released

( vlax-read-enabled-p obj)

Determines whether an object can be read

( vlax-release-object obj)

Releases a drawing object

( vlax-typeinfo-available-p obj)

Determines whether type library information is present for the specified type of object

( vlax-write-enabled-p obj)

Determines whether an AutoCAD drawing object can be modified


Reactor Functions

Functions for Handling Drawing Objects
AutoLISP Function Synopsis
VLX Namespace Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Reactor Functions

Reactor functions define, query, and delete reactors and reactor properties.

NoteBefore you can use these functions, you must load AutoLISP reactor support by issuing the following command:

(vl-load-com)

The vl-load-com function initializes reactor support and a number of other AutoLISP extensions.

Reactor functions

Function

Description

( vl-load-com)

Loads AutoLISP reactor support functions and other AutoLISP extensions

( vlr-acdb-reactor datacallbacks)

Constructs a database (global) reactor object

( vlr-add obj)

Enables a disabled reactor object

( vlr-added-p obj)

Tests to determine whether a reactor object is enabled

( vlr-beep-reaction [args])

Produces a beep sound

( vlr-current-reaction-name)

Returns the name (symbol) of the current event, if called from within a reactor's callback

( vlr-data obj)

Returns application-specific data associated with a reactor

( vlr-data-set objdata)

Overwrites application-specific data associated with a reactor

( vlr-deepclone-reactor objdata)

Constructs an editor reactor object that provides notification of deep clone events

( vlr-docmanager-reactor

objdata)

Constructs a reactor object that provides notification of MDI-related events

( vlr-dwg-reactor objdata)

Constructs an editor reactor object that provides notification of a drawing event (for example, opening or closing a drawing file)

( vlr-dxf-reactor objdata)

Constructs an editor reactor object that notifies of an event related to reading or writing of a DXF file

( vlr-editor-reactor data

callbacks)

Constructs an editor (global) reactor object

( vlr-linker-reactor data

callbacks)

Constructs a linker (global) reactor object

( vlr-miscellaneous-reactor

datacallbacks)

Constructs an editor reactor object that does not fall under any of the other editor reactor types

( vlr-mouse-reactor

datacallbacks)

Constructs an editor reactor object that provides notification of a mouse event (for example, a double-click)

( vlr-notification reactor)

Determines whether or not a reactor's callback function will execute if its associated namespace is not active

( vlr-object-reactor owners

datacallbacks)

Constructs an object reactor object

( vlr-owner-add reactorowner)

Adds an object to the list of owners of an object reactor

( vlr-owner-remove

reactorowner)

Removes an object from the list of owners of an object reactor

( vlr-owners reactor)

Returns the list of owners of an object reactor

( vlr-pers reactor)

Makes a reactor persistent

( vlr-pers-list [reactor])

Returns a list of persistent reactors in the current drawing

( vlr-pers-p reactor)

Determines whether or not a reactor is persistent

( vlr-pers-release reactor)

Makes a reactor transient

( vlr-reaction-name reactor-type)

Returns a list of all callback conditions for this reactor type

( vlr-reaction-set reactoreventfunction)

Adds or replaces a callback function in a reactor

( vlr-reactions reactor)

Returns a list of pairs (event-name . callback_function) for the reactor

( vlr-reactors [reactor-type...])

Returns a list of reactors of the specified types

( vlr-remove reactor)

Disables a reactor

( vlr-remove-all reactor-type)

Disables all reactors of the specified type

( vlr-set-notification reactor

'range)

Defines whether or not a reactor's callback function will execute if its associated namespace is not active

( vlr-sysvar-reactor data

callbacks)

Constructs an editor reactor object that provides notification of a change to a system variable

( vlr-toolbar-reactor data

callbacks)

Constructs an editor reactor object that provides notification of a change to the bitmaps in a toolbar

( vlr-trace-reaction)

A pre-defined callback function that prints one or more callback arguments in the Trace window

( vlr-type reactor)

Returns a symbol representing the reactor type

( vlr-types)

Returns a list of all reactor types

( vlr-undo-reactor data

callbacks)

Constructs an editor reactor object that provides notification of an undo event

( vlr-wblock-reactor data

callbacks)

Constructs an editor reactor object that provides notification of an event related to writing a block

( vlr-window-reactor datacallbacks)

Constructs an editor reactor object that notifies of an event related to moving or sizing an AutoCAD window

( vlr-xref-reactor datacallbacks)

Constructs an editor reactor object that provides notification of an event related to attaching or modifying XREF


VLX Namespace Functions

Reactor Functions
AutoLISP Function Synopsis
Namespace Communication Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
VLX Namespace Functions

The VLX namespace functions listed below apply to separate-namespace VLX applications. These functions allow separate-namespace VLX functions to be accessible from a document namespace, enable the retrieval and updating of variables in the associated document namespace, and provide error-handling routines for separate-namespace VLX functions.

VLX namespace functions

Function

Description

( vl-arx-import

[function | application]

Imports ADS-DEFUN functions into a separate-namespace VLX

( vl-doc-export 'function)

Makes a function loaded in a VLX namespace available to the current document

( vl-doc-import

['function | application])

Imports a function that was previously exported from another separate-namespace VLX

( vl-doc-ref symbol)

Retrieves the value of a variable from the namespace of the associated document

( vl-doc-set symbolvalue)

Sets the value of a variable in the associated document's namespace

( vl-exit-with-error “msg”)

Passes control from a VLX error handler to the *error* function of the associated document namespace

( vl-exit-with-value value)

Returns a value to the document namespace from which the VLX was invoked

( vl-list-exported-functions [“appname”])

Lists all functions exported by the specified application, or all exported functions if no application is specified

( vl-list-loaded-vlx)

Returns a list of all separate-namespace VLX files associated with the current document

( vl-unload-vlx “appname”)

Unloads a VLX that is loaded in its own namespace (a separate-namespace VLX)

( vl-vlx-loaded-p “appname”)

Determines whether a VLX is loaded in its own namespace


Namespace Communication Functions

VLX Namespace Functions
AutoLISP Function Synopsis
Windows Registry Functions
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Namespace Communication Functions

The namespace communication functions consist of blackboard addressing and multi-document-loading functions.

Namespace communication functions

Function

Description

( vl-bb-ref 'variable)

Returns the value of a variable from the blackboard namespace

( vl-bb-set 'variable value)

Sets the value of a variable in the blackboard namespace

( vl-load-all “filename”)

Loads a file into all open AutoCAD documents, and into any document subsequently opened during the current AutoCAD session

( vl-propagate 'variable)

Copies the value of a variable into all open AutoCAD documents, and into any document subsequently opened during the current AutoCAD session


Windows Registry Functions

Namespace Communication Functions
AutoLISP Function Synopsis
Visual LISP Environment and Formatting Options
AutoLISP Developer's Guide > Appendixes > AutoLISP Function Synopsis >
Windows Registry Functions

Windows Registry functions query and update the Windows Registry.

Windows Registry functions

Function

Description

( vl-registry-delete reg-key

[val-name])

Deletes the specified key or value from the Windows Registry

( vl-registry-descendents reg-key

[val-names])

Returns a list of subkeys or value names for the specified Registry key

( vl-registry-read reg-key

[val-name])

Returns data stored in the Windows Registry for the specified key/value pair

( vl-registry-write reg-key

[val-name val-data])

Creates a key in the Windows Registry

( vlax-product-key)

Returns the AutoCAD registry path

NoteThis is an extended function provided by VLISP. You must issue vl-load-com before you can use the function.


Visual LISP Environment and Formatting Options

Windows Registry Functions
Appendixes
Window Attributes Options
AutoLISP Developer's Guide > Appendixes >
Visual LISP Environment and Formatting Options

Color-coding options, diagnostic options, and page layout options are described.

This chapter describes the configuration options available on the Visual LISP® Tools menu. The Window Attributes options set color-coding for the VLISP text editor windows. Using Environment Options on the Tools menu, you can set session-wide VLISP options (for example, whether or not to create automatic backup files, or how to treat protected symbols), diagnostic options (such as what statistics to report during syntax checking, or what level of detail to display when inspecting drawing objects), formatting options for AutoLISP® code, and page layout options for printed output.

Topics in this section

  • Window Attributes Options
  • Environment Options
  • Save Settings (Tools Menu)


Window Attributes Options

Visual LISP Environment and Formatting Options
Visual LISP Environment and Formatting Options
Syntax Coloring
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options >
Window Attributes Options

On the Visual LISP Tools menu, the Window Attributes submenu includes options for customizing the VLISP windowing environment, controlling attributes such as colors, fonts, and code formatting. The Syntax Coloring, Current to Prototype, and All to Prototype options are available only for text editor windows.

VLISP allows you to define prototype configurations for text editor windows. The prototype becomes the default configuration for these windows. For example, when you open a new file in the VLISP text editor, the editor window assumes the attributes and properties of the prototype editor configuration. The window prototype includes

  • Color scheme
  • Lexical coloring flag
  • Tab size
  • Left margin indent

Every time you change and save any text editor window attribute settings, VLISP will ask you if the modified setting should be used as a prototype for the window type.

Topics in this section

  • Syntax Coloring
  • Configure Current
  • Set Current Window to Prototype
  • Set All Windows to Prototype
  • Font


Syntax Coloring

Window Attributes Options
Window Attributes Options
Configure Current
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Window Attributes Options >
Syntax Coloring

On the Visual LISP Tools menu, on the Window Attributes submenu, the Syntax Coloring option determines the type of syntax coloring that will be used for the current file being edited. This option is available when you edit a file whose file type is not .lsp. When chosen, Syntax Coloring displays the Color Style dialog box, which provides the following options:

None

No color coding.

AutoLISP

Use AutoLISP syntax color coding. This color coding scheme is used for all files of type .lsp.

C++

Use C++ syntax color coding. This is the default for all files of type .cpp, .c++, .c, .hpp, .h++, and .h.

DCL

Use DCL syntax color coding. This is the default for all files of type .dcl.

SQL

Use SQL syntax color coding. This is the default for all files of type .sql.

If a file type does not have a default coloring style, the user is asked whether to use the selected coloring style for all files of the same type.

NoteAll formatting and “smart” indentation features require the AutoLISP lexical coloring style.


Configure Current

Syntax Coloring
Window Attributes Options
Set Current Window to Prototype
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Window Attributes Options >
Configure Current

On the Visual LISP Tools menu, on the Window Attributes submenu, the Configure Current option allows you to configure the attributes of the current window. It is applicable to the VLISP text editor and Console windows. The Configure Current option displays the Window Attributes dialog box:

This dialog box lets you customize the tab width and left margin sizes, customize various text colors defined for the current window type, and control the lexical coloring for that window (if applicable). To select the color with the aid of the color selection control, click the mouse button in the rectangle that is painted with the color you want to set.

Text Colors

The upper row of rectangles indicates foreground color; the lower row indicates background color. When you select a color, the color palette changes its color with respect to your choice. Use the pull-down list to select the attribute of the window whose colors you want to change. The available choices depend on which window is current. The following are possible window attributes:

  • :Input-Zone. The input area following the Console window prompt.
  • :Window-Text. Text displayed in the window (other than input zone).
  • :Window-Selection. Selected text.
  • :Error-Highlight. Error messages in the Build Output window.
  • :Console-Message. No effect (reserved for future use).
  • :BPT-Active. Active breakpoint.
  • :BPT-Disable. Disabled breakpoint.

The pull-down list may also provide options for changing the lexical coloring of the following AutoLISP code components:

  • :LEX-SPACE. Spaces.
  • :LEX-STR. Strings.
  • :LEX-SYM. Symbols.
  • :LEX-NUM. Reserved for future use.
  • :LEX-INT. Integers.
  • :LEX-REAL. Real numbers.
  • :LEX-COMM. Reserved for future use.
  • :LEX-COMM1. Comments that begin with one or more semicolons.
  • :LEX-COMM2. Inline and multi-line comments (comments that begin with ;| and end with |;).
  • :LEX-PAREN. Parentheses.
  • :LEX-SPEC. Reserved for future use.
  • :LEX-SPEC1. Reserved for future use.
  • :LEX-UNKN. Unknown items.
Transparent FG

Transparent foreground.

Transparent BG

Transparent background.

Lexical Colors

If this option is selected, VLISP applies the selected color coding options. If you want to use the VLISP formatter but do not want lexical coloring, turn this option off.

Tab Width

Sets tab spacing in the current window.

Left Margin

Sets the left margin of the current window.

When you change and save the configuration of a VLISP editor window, you will be asked whether or not you want the configuration to become the prototype for all text editor windows. If you choose Yes, the configuration of the current window becomes the new prototype for VLISP text editor windows, and all open text editor windows assume the attributes of the prototype.


Set Current Window to Prototype

Configure Current
Window Attributes Options
Set All Windows to Prototype
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Window Attributes Options >
Set Current Window to Prototype

On the Visual LISP Tools menu, on the Window Attributes submenu, the Set Current Window to Prototype option configures the current active window with the attributes of the prototype window.


Set All Windows to Prototype

Set Current Window to Prototype
Window Attributes Options
Font
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Window Attributes Options >
Set All Windows to Prototype

On the Visual LISP Tools menu, on the Window Attributes submenu, the Set All Windows to Prototype option sets all open windows with the attributes of the prototype.


Font

Set All Windows to Prototype
Window Attributes Options
Environment Options
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Window Attributes Options >
Font

On the Visual LISP Tools menu, on the Window Attributes submenu, the font option opens a standard Windows Font dialog box where you can select the font to be used in VLISP windows.

Note that for code formatting to work correctly, you must use a fixed (non-proportional) font.


Environment Options

Font
Visual LISP Environment and Formatting Options
General Options Dialog Box
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options >
Environment Options

On the Visual LISP Tools menu, the Environment Options submenu allows you to set session-wide VLISP options. For example, you can tell VLISP whether to save text editor files at set intervals automatically, whether to create automatic backup files, and how you want to treat attempts to modify protected symbols. Environment Options is also where you set diagnostic options, such as what statistics to report during syntax checking, and what level of detail to display when inspecting drawing objects. You can also set formatting options for AutoLISP code, and page layout options for printed output.

Topics in this section

  • General Options Dialog Box
  • Visual LISP Format Options
  • Page Format Options in the Page Setup Dialog Box


General Options Dialog Box

Environment Options
Environment Options
General Tab (General Options Dialog Box)
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options >
General Options Dialog Box

On the Visual LISP Tools menu, on the Environment Options submenu, the General Options option displays the General Options dialog box containing the General and Diagnostic tabs.

Topics in this section

  • General Tab (General Options Dialog Box)
  • Diagnostic Tab (General Options Dialog Box)


General Tab (General Options Dialog Box)

General Options Dialog Box
General Options Dialog Box
Diagnostic Tab (General Options Dialog Box)
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options > General Options Dialog Box >
General Tab (General Options Dialog Box)

On the Visual LISP Tools menu, on the Environment Options submenu, the General Options option displays the General Options dialog box. In the General Options dialog box, on the General tab, there are three groups of options: Editor Options, Desktop, and SETQ to Protected Symbols.

The Editor Options group contains the following options:

Backup the File Edited on First Save

When this option is selected, VLISP creates a backup copy of the file the first time you save it.

Make Backup by Copy, Not Rename

VLISP creates a copy of the original file. When this option is not selected, the backup file is a renamed version of the original file.

Group Typing for Undo/Redo

VLISP groups keystrokes for the Undo and Redo Edit commands. If this option is not selected, Undo and Redo proceed one character at a time.

The Desktop group contains the following options:

Save Editor Windows Settings

The VLISP text editor window settings (toolbar placement and text/background color) will be saved along with window sizes, placements, and editor configurations when you use the Save Settings option on the Tools menu. When the Save Editor Windows Setting option is off, VLISP editor window settings are not saved.

Autosave Setting on Exit Application

If Save Editor Windows Settings is turned on, then when you exit VLISP, the VLISP text editor window settings (toolbar placement and text/background color) are saved along with window sizes, placements, and editor configuration.

The SETQ to Protected Symbols group controls how VLISP responds to attempts to redefine protected symbols. (See Protected Symbols.) The options are as follows:

Transparent

When this option is selected, protected symbols are treated like any other symbol.

Print Message

When this option is selected, AutoLISP issues a warning message when you modify a protected symbol but carries out the modification.

Prompt to Enter Break Loop

When this option is selected, AutoLISP displays a message box asking whether or not to enter a break loop when you attempt to modify a protected symbol. This option is the default. If you choose No, the symbol's value is modified and processing continues normally.

If you choose Yes, processing is interrupted and you enter a VLISP break loop. In a break loop, control switches to the VLISP Console window. You can set the symbol and continue processing by pressing the Continue button on the VLISP toolbar, or you can abort modification by pressing Reset.

Error

When this option is selected, modification of protected symbols is prohibited. Any attempt to modify a protected symbol results in an error.


Diagnostic Tab (General Options Dialog Box)

General Tab (General Options Dialog Box)
General Options Dialog Box
Visual LISP Format Options
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options > General Options Dialog Box >
Diagnostic Tab (General Options Dialog Box)

On the Visual LISP Tools menu, on the Environment Options submenu, the General Options option displays the General Options dialog box. In the General Options dialog box, on the Diagnostic tab, the options control how VLISP provides information about AutoLISP syntax.

The Diagnostic tab's options are as follows:

Report Statistics During Syntax Checking

If this option is selected, the syntax checker and the file compiler report the statistics after checking or compiling each top-level form and after each file.

Print Top Level Results On Load

If this option is selected, top-level expressions are evaluated and printed in the Console window when the expressions are loaded.

A top-level expression is one that appears outside any other expression (for example, an expression that appears outside of defun). For example, the following call to list is a top-level expression:

(list 1 2 3)

(defun foo (x) x)

Loading a file containing this code results in the following being printed in the Console window, if Print Top Level Results on Load is selected:

(1 2 3)

FOO

Print Notification Message After Load

If this option is selected, each call to the load function results in messages printed to the VLISP Console window.

Echo PRINx Output to ACAD

If this option is selected, the default output of functions print, princ and prin1 is echoed to the AutoCAD Command window and the VLISP Console window instead of only to the VLISP Console window.

Inspect Drawing Objects Verbosely

If this option is selected, the elements of an object are included in the Inspect window for a drawing database object. If the option is not selected, only the object line (containing the entity name) appears in drawing object Inspect windows.

Do Not Debug Top-Level

If this option is selected and Stop Once mode is set, the break will not occur before evaluating every top-level form (such as defun) during the file load process.

Animation Delay

Determines the pause length between program steps in Animate mode, measured in milliseconds. The default is 100.


Visual LISP Format Options

Diagnostic Tab (General Options Dialog Box)
Environment Options
Base Formatting Options in the Format Options Dialog Box
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options >
Visual LISP Format Options

On the Visual LISP Tools menu, on the Environment Options submenu, the Visual LISP Format Options option displays the Format Options dialog box, which is used to set formatting and indentation options.

Additional formatting options are available by pressing the More Options button. These options are covered in Additional Formatting Options in the Format Options Dialog Box.

Pressing Revert to Default reverts the option settings to the previous saved setting, or to the system default, if the user has not previously changed and saved settings.

Note that the code formatter assumes that you are using a fixed font to display or print formatted text.

Topics in this section

  • Base Formatting Options in the Format Options Dialog Box
  • Additional Formatting Options in the Format Options Dialog Box


Base Formatting Options in the Format Options Dialog Box

Visual LISP Format Options
Visual LISP Format Options
Additional Formatting Options in the Format Options Dialog Box
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options > Visual LISP Format Options >
Base Formatting Options in the Format Options Dialog Box

The following options are shown at the top of the Format Options dialog box.

Right Text Margin

Right margin for text. An expression prints on a single line if its last character position does not exceed the right margin.

Narrow Style Indentation

Sets the standard indentation value used in the Narrow Formatting Style for function arguments.

Maximum Wide-Style Car Length

Maximum length for function expressions in Wide Formatting Style. For longer expressions, the formatter always uses Narrow Formatting Style.

Single-Semicolon Comment Indentation

Identifies the left margin alignment for single-semicolon comments.

The Closing Paren Style group of options controls the position of closing parentheses for multi-line formatting styles. The effect of each option is demonstrated by formatting the following code, where Right Text Margin is set to 40 and Preserve Existing Line Breaks is not selected:

(cond
 ((/= (logand mask flg) 0)
 (list (list txton)))
)

VLISP formats the preceding code as follows:

Close at the Same Line

(cond ((/= (logand mask flg) 0)

(list (list txton))))

Close at the New Line with Inner Indentation

(cond ((/= (logand mask flg) 0)

(list (list txton))

)

)

Close at The New Line with Outer Indentation

(cond ((/= (logand mask flg) 0)

(list (list txton))

)

)

The remaining items in this dialog box concern tabs, saving the current setting, and the setting of several comment options.

Insert Tabs

The VLISP formatter inserts tab characters instead of multiple space characters whenever possible.

Save Formatting Options in Source File

The VLISP formatter appends comments containing the current formatting settings to the end of the text in the VLISP text editor window. If you save these comments (and do not modify them), VLISP applies the saved formatting options to the text editor the next time you open the file.

Insert Form-Closing Comment

This option causes VLISP to add a closing comment to an expression when Close at the New Line with Inner Indentation or Close at the New Line with Outer Indentation is selected. The comment takes the following form at the end of a multi-line function:

;_ end of <function name>

VLISP does not add the comment if the line already contains a comment.

Form-Closing Comment Prefix

Determines the text to be included when Insert Form-Closing Comment is selected.


Additional Formatting Options in the Format Options Dialog Box

Base Formatting Options in the Format Options Dialog Box
Visual LISP Format Options
Page Format Options in the Page Setup Dialog Box
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options > Visual LISP Format Options >
Additional Formatting Options in the Format Options Dialog Box

Additional formatting options appear when you press the More Options button in the Format Options dialog box.

Approximate Line Length

The VLISP formatter checks this value when it chooses the formatting style. If the number of characters in an expression is greater than this value, the formatter prints the expression as multi-line.

Preserve Existing Line Breaks

When this option is selected, the VLISP formatter inserts new lines whenever a new line is detected in the text being formatted. When the option is off, the formatter can squeeze a multiple-line expression to the plane style, if it fits within the right margin.

NoteSelecting this option causes VLISP to ignore other formatting options when those options would result in a loss of existing line breaks. This is often the source of unexpected formatting results.
Split Comments

When this option is selected, the VLISP formatter splits comments that exceed the right margin.

Casing for Symbols

These options control whether or not the VLISP formatter converts the case of alphabetic text in an AutoLISP symbol name. The protected symbols subgroup controls the case conversion of protected symbols (that is, symbols with the ASSIGN-PROTECT flag set). The unprotected options subgroup controls the case conversion of unprotected AutoLISP symbols. The following options are available:

None: No case conversion.

Downcase: The formatter converts all characters in a symbol name to lowercase.

Upcase: The formatter converts all characters in a symbol name to uppercase.

The Long List format style option controls the formatting of long lists. Long lists are lists of formal arguments in defun and lambda expressions, or in quoted lists of atoms with more than five elements. The style option applies to long lists that do not fit on a single line (that is, within the Right Text Margin). Long List format style options are illustrated by formatting the following statement with Right Text Margin set to 45:

(setq lista '("abc" "def" "ghi" "jkl" "mno" "pqr"))

The options are as follows

Single-Column Formatting

(setq lista '("abc"

"def"

"ghi"

"jkl"

"mno"

"pqr"

)

)

2-Column Formatting

(setq listall '("abc" "def"

"ghi" "jkl"

"mno" "pqr"

)

)

Multi-Column Formatting

(setq listall '("abc" "def" "ghi"

"jkl" "mno" "pqr"

)

)

Fill-to-Margin Formatting

(setq listall '("abc" "def" "ghi" "jkl" “mno”

"pqr"

)

)


Page Format Options in the Page Setup Dialog Box

Additional Formatting Options in the Format Options Dialog Box
Environment Options
Justification and Substitution Codes in the Page Setup Dialog Box
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options >
Page Format Options in the Page Setup Dialog Box

Page format options are shown in the Page Setup Dialog Box.

The following options control the appearance of printed output from VLISP:

Header and Footer

Fields for specifying the content of the page header and footer. The first input field contains the header line to print at the top of the page; the second input field contains the footer line to print at the bottom of the page. Headers and footers may contain text strings and variables. See Justification and Substitution Codes in the Page Setup Dialog Box for more information on specifying headers and footers.

Print Page Margins

Select either inches or millimeters as the measuring unit, then specify Top, Left, Bottom, and Right margins.

Font Button

Choose the Font button to open the Font dialog box for specifying the output font.

Topics in this section

  • Justification and Substitution Codes in the Page Setup Dialog Box


Justification and Substitution Codes in the Page Setup Dialog Box

Page Format Options in the Page Setup Dialog Box
Page Format Options in the Page Setup Dialog Box
Save Settings (Tools Menu)
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options > Environment Options > Page Format Options in the Page Setup Dialog Box >
Justification and Substitution Codes in the Page Setup Dialog Box

When you specify a header and footer in the Page Setup dialog box, only the ampersand character (&) is considered as an escape character. Both the ampersand and the character that follows are not copied to the output line. Instead, they either justify the following text, or VLISP replaces them with variable information.

In the Page Setup dialog box, justification codes indicate how header text is justified on the printed page. You can specify any of the following:

&l

Left-justified (the default).

&c

Centered within the page margins.

&r

Right-justified.

In the Page Setup dialog box, replace codes are variables for which VLISP substitutes values. Specify any of the following:

&f

VLISP replaces this code with the title of the active VLISP window. When invoked from a VLISP text editor window, &f is the name of the file being edited, including directory and extension.

&d

Current system date. To select a date format, choose Edit [image] Extra Commands [image] Format Date/Time from the VLISP menu.

&t

Current system time. To select a time format, choose Edit [image] Extra Commands [image] Format Date/Time from the VLISP menu.

&p

Current page number.

To include an ampersand character in your heading text, enter two in succession.

The default heading is set to the following:

&cFile: &f &r&dt

The default footing is set as follows:

&r&p

The following is a sample printed page from an AutoLISP source file using the default page layout settings:

            File: REACTORSTUFF.LSP            12/11/98
(defun saveDrawingInfo (calling-reactor commandInfo / dwgname filesize)
  (setq dwgname (cadr commandInfo)
     filesize (vl-file-size dwgname)
  )
  (alert (strcat "The file size of “ dwgname “ is “))
.
.
.
 (princ)
)
                                             2


Save Settings (Tools Menu)

Justification and Substitution Codes in the Page Setup Dialog Box
Visual LISP Environment and Formatting Options
AutoLISP Error Codes
AutoLISP Developer's Guide > Appendixes > Visual LISP Environment and Formatting Options >
Save Settings (Tools Menu)

The Save Settings option on the Visual LISP Tools menu saves the desktop configuration and options settings. Note that the desktop configuration for the child windows attributes (their presence on the screen, color, position, files loaded) is saved only when the Save Editor Windows Settings option in the General Options dialog box is turned on.


AutoLISP Error Codes

Save Settings (Tools Menu)
Appendixes
Error Codes
AutoLISP Developer's Guide > Appendixes >
AutoLISP Error Codes

The error codes generated by AutoLISP are described.

This appendix lists the AutoLISP® error codes.

Topics in this section

  • Error Codes


Error Codes

AutoLISP Error Codes
AutoLISP Error Codes
AutoLISP Developer's Guide > Appendixes > AutoLISP Error Codes >
Error Codes

The following table shows the values of error codes generated by AutoLISP. The ERRNO system variable is set to one of these values when an AutoLISP function call causes an error that AutoCAD detects. AutoLISP applications can inspect the current value of ERRNO with (getvar "errno").

The ERRNO system variable is not always cleared to zero. Unless it is inspected immediately after an AutoLISP function has reported an error, the error that its value indicates may be misleading. This variable is always cleared when starting or opening a drawing.

NoteThe possible values ofERRNO, and their meanings, are subject to change.
Online program error codes
Value | Meaning
0 | No error
1 | Invalid symbol table name
2 | Invalid entity or selection set name
3 | Exceeded maximum number of selection sets
4 | Invalid selection set
5 | Improper use of block definition
6 | Improper use of xref
7 | Object selection: pick failed
8 | End of entity file
9 | End of block definition file
10 | Failed to find last entity
11 | Illegal attempt to delete viewport object
12 | Operation not allowed during PLINE
13 | Invalid handle
14 | Handles not enabled
15 | Invalid arguments in coordinate transform request
16 | Invalid space in coordinate transform request
17 | Invalid use of deleted entity
18 | Invalid table name
19 | Invalid table function argument
20 | Attempt to set a read-only variable
21 | Zero value not allowed
22 | Value out of range
23 | Complex REGEN in progress
24 | Attempt to change entity type
25 | Bad layer name
26 | Bad linetype name
27 | Bad color name
28 | Bad text style name
29 | Bad shape name
30 | Bad field for entity type
31 | Attempt to modify deleted entity
32 | Attempt to modify seqend subentity
33 | Attempt to change handle
34 | Attempt to modify viewport visibility
35 | Entity on locked layer
36 | Bad entity type
37 | Bad polyline entity
38 | Incomplete complex entity in block
39 | Invalid block name field
40 | Duplicate block flag fields
41 | Duplicate block name fields
42 | Bad normal vector
43 | Missing block name
44 | Missing block flags
45 | Invalid anonymous block
46 | Invalid block definition
47 | Mandatory field missing
48 | Unrecognized extended data (XDATA) type
49 | Improper nesting of list in XDATA
50 | Improper location of APPID field
51 | Exceeded maximum XDATA size
52 | Entity selection: null response
53 | Duplicate APPID
54 | Attempt to make or modify viewport entity
55 | Attempt to make or modify an xref, xdef, or xdep
56 | ssget filter: unexpected end of list
57 | ssget filter: missing test operand
58 | ssget filter: invalid opcode (-4) string
59 | ssget filter: improper nesting or empty conditional clause
60 | ssget filter: mismatched begin and end of conditional clause
61 | ssget filter: wrong number of arguments in conditional clause (for NOT or XOR)
62 | ssget filter: exceeded maximum nesting limit
63 | ssget filter: invalid group code
64 | ssget filter: invalid string test
65 | ssget filter: invalid vector test
66 | ssget filter: invalid real test
67 | ssget filter: invalid integer test
68 | Digitizer is not a tablet
69 | Tablet is not calibrated
70 | Invalid tablet arguments
71 | ADS error: Unable to allocate new result buffer
72 | ADS error: Null pointer detected
73 | Cannot open executable file
74 | Application is already loaded
75 | Maximum number of applications already loaded
76 | Unable to execute application
77 | Incompatible version number
78 | Unable to unload nested application
79 | Application refused to unload
80 | Application is not currently loaded
81 | Not enough memory to load application
82 | ADS error: Invalid transformation matrix
83 | ADS error: Invalid symbol name
84 | ADS error: Invalid symbol value
85 | AutoLISP/ADS operation prohibited while a dialog box was displayed


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