2012

Table Of Contents
creating AutoLISP routines you can add discipline-specific commands to
AutoCAD. Some of the standard AutoCAD commands are actually AutoLISP
applications.
Visual LISP provides three file format options for AutoLISP applications:
Reading an LSP file (.lsp)an ASCII text file that contains AutoLISP program
code.
Reading an FAS file (.fas)a binary, compiled version of a single LSP
program file.
Reading a VLX file (.vlx)a compiled set of one or more LSP and/or dialog
control language (DCL) files.
NOTE Like-named AutoLISP application files are loaded based on their Modified
time stamp; the LSP, FAS, or VLX file with the most recent time stamp is loaded
unless you specify the full file name (including the file name extension).
Because AutoCAD can read AutoLISP code directly, no compiling is required.
While Visual LISP provides an IDE, you may choose to experiment by entering
code at the command prompt, which allows you to see the results immediately.
This makes AutoLISP an easy language to experiment with, regardless of your
programming experience.
Even if you are not interested in writing AutoLISP applications, your AutoCAD
package includes many useful routines. Routines are also available as shareware
through third-party developers. Knowing how to load and use these routines
can enhance your productivity.
NOTE When command input comes from the AutoLISP command function, the
settings of the PICKADD and PICKAUTO system variables are assumed to be 1 and
0, respectively. This preserves compatibility with previous releases of AutoCAD
and makes customization easier (because you don't have to check the settings of
these variables).
For information about AutoLISP programming, see the AutoLISP Developer's
Guide, and for information about AutoLISP and Visual LISP functions, see the
AutoLISP Reference in the Help system. To display Developer Help, on the
InfoCenter toolbar, to the right of the Help button, click the drop-down arrow.
From the menu, click Additional Resources Developer Help. AutoLISP
programs can use dialog boxes with their applications. Programmable dialog
boxes are described only in the AutoLISP Developer's Guide.
434 | Chapter 7 Introduction to Programming Interfaces