vlaxreleaseobject

vlax-release-object is a Visual LISP function used in AutoCAD and other Autodesk products to release a COM/ActiveX object that was created or obtained through Visual Lisp. The function helps manage memory and resource usage by unbinding the Lisp wrapper from the underlying COM object and allowing the object’s reference to be released, which can reduce leaks in long-running scripts or batch operations.

Syntax and usage

The function takes a single argument: the Visual Lisp handle to a COM object (for example, one obtained via vlax-create-object or vlax-get-object). The typical usage pattern is to perform all required operations with the object and then call (vlax-release-object obj) when finished. After releasing, the Lisp reference should not be used again for that object, and it is common to set the variable to nil to avoid accidental reuse.

Return value

The function primarily provides a side-effect: releasing the underlying object. Its return value is not generally used for further computation, and in practice it is often nil.

Considerations

Releasing an object does not necessarily terminate the server if other references exist. If multiple handles to the same COM object are in use, releasing one handle decreases the reference count but may not fully unload the object. It is good practice to release all handles when they are no longer needed and to set variables to nil after release to prevent accidental access.

Related functions

Commonly used alongside vlax-create-object, vlax-get-property, and vlax-put-property, vlax-release-object helps manage the lifecycle of COM automation in Visual Lisp scripts.