COM: Returning IDispatch or NULL

[Mark Hammond]

Juan Carlos CORUÑA wrote:
> Hello,
> 
> I'm trying to develop a COM Server in python, that has a method that
> returns an IDispatch object but sometimes it must return nothing. See
> the following example programmed in C/SIDE (Microsoft Navision
> Financials ERP):
> 
> --->
> otherCOMServer := COMServer.returnOtherCOMServer();
> IF ISCLEAR(otherCOMServer) THEN MESSAGE('otherCOMServer is clear');
> <----
> 
> Definition of ISCLEAR (extracted from MS Navision help):
>   The return value is TRUE if:
>     -the automation variable has not been created. See CREATE.
>     -the automation variable has been cleared. See CLEAR.
>     -the automation variable has been assigned NULL by an automation
> server.
> 
> I thing that in this case I must assign NULL to the otherCOMServer
> variable in order to keep the otherCOMServer variable CLEARED.
> What must I return from "COMServer.returnOtherCOMServer()" method to
> assign NULL?
> I have tried:
>   return None
>   return wrap(None)
>   return 1==0
>   return
> 
> but without success. The environment responds "data type not
> supported".

None is the way to do this.  What responds "data type not supported"? 
Have you registered your object for debugging and seen the output? 
There may be a traceback printed.

Mark.