About Extended AutoLISP Functions (AutoLISP/ActiveX)

The AutoLISP programming language offers a wide range of functions that are loaded automatically when you start AutoCAD, but not all functions are loaded by default.

Note: Functions beginning with vla-, vlax-, and vlr- are not available for use with AutoCAD for Mac.

Those that are not loaded automatically are known as the “extension or extended functions”.

The extension functions have names that begin with

• vla- functions implement ActiveX® support in AutoLISP.
• vlax- functions provide ActiveX utility and data conversion functions, dictionary handling functions, and curve measurement functions.
• vlr- functions provide support for AutoCAD reactors.

Before you can use any of these functions, you must load the AutoLISP extensions with the vl-load-com function. The vl-load-com function does not accept any arguments.

For example:

(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 might fail.