User warning: assignment to protected symbol – when using vlax-import-type-library

By Adam Nagy

When I load my dll then I get this warning:

; User warning: assignment to protected symbol: CLOSE <- #

Also, when loading the dll for the second time, I get similar warnings for all the functions the dll contains.

Shall I just ignore these warnings?

Solution

You can and should avoid these warnings by using prefixes for the imported dll methods/properties/constants.

The best things is to use your registered developer symbol plus m/p/c depending on if it's for methods, properties or constants.

Also you can find out if the dll has already been loaded by checking if any of the methods/properties/constants are available (i.e. does not equal nil), and if they are not, only then load your dll.

Here is a sample code using my registered developer symbol, AEN1:

(defun c:loadmydll ( )
 (vl-load-com)
 ; Check if a specific function that is part of the dll
 ; if not, then the dll is not yet loaded
 ; so we load it now 
 ; This specific dll contains a function called close, 
 ; so I'm checking for that 
 (if (equal nil aen1m-close)
  (vlax-import-type-library
   :tlb-filename "C:/Test/lispCOM.dll"
   :methods-prefix "aen1m-"
   :properties-prefix "aen1p-"
   :constants-prefix "aen1c-"
  )
 )   
)