Function Entry: VL-ACAD-UNDEFUN

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Function Entry: VL-ACAD-UNDEFUN

Name

vl-acad-undefun

Class

Visual LISP external-exposure function

Syntax

(vl-acad-undefun 'symbol)

Arguments and Values

  • symbol — subroutine or symbol naming a function.

Description

Undefines an AutoLISP function symbol so it is no longer available to ObjectARX applications.

Return Values

Returns an integer if successful; returns nil if unsuccessful.

Side Effects

Removes external visibility of the designated function.

Notes

  • Autodesk documents use on c: functions and functions previously exposed with vl-acad-defun.

Availability

  • AutoCAD 2026: documented (per Autodesk reference page).
  • AutoCAD 2022: verified present as a SUBR by runtime probe 2026-08-09.
  • BricsCAD V25 and V26: verified present as a SUBR by runtime probe 2026-08-09. The Bricsys DevRef "VLX NameSpace Support" page documents the family as supported since V18.2 (DEScoder v2.7+).
  • Status: verified on both vendors (no longer "presumed compatible"); see chapter 22 § VLX namespace family: verification 2026-08-09.