Re: Problem with C function pointers

[Stephen Leake <stephen_leake@acm.org>]

skibochka@yahoo.com (Andrew Skiba) writes:

> The question is how do I eliminate the check? 

You don't want to eliminate the check! but you do want to solve the
problem. 

> type SetCooperativeLevel_func is access function
> (thiz:IDirectFBCore_ptr; level:CooperativeLevel) return DFBResult;
> pragma Convention (C, SetCooperativeLevel_func); -- this does not help
> type IDirectFBCore is record
>   ...
>   SetCooperativeLevel:SetCooperativeLevel_func; -- this field
>     -- points to some C function inside DirectFB library
>   ...
> end record;
> pragma Convention (C, IDirectFBCore); -- this does not help, too :-(
> thiz:IDirectFBCore;
> f:SetCooperativeLevel_func;
> 
> f:=thiz.SetCooperativeLevel; -- here exception is raised

Hmm. At this point "thiz" has the value "null". What do you expect?

I suspect you left out some code, that sets "thiz". please post a
small compilable example, if possible.

Have you tried running under gdb, and examining "thiz"?

Just out of curiosity, what does DirectFB do?
-- 
-- Stephe