Re: Translating a VB dll header to Ada

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 14 Apr 2007 05:16:33 -0700, vienapl@hotmail.com wrote:

> Yes, it does work with only those two functions.
> 
> I don't know which parameter could be wrong on the CTHSetText
> function. If I change a Char_Array for a WChar_Array I get a raised
> PROGRAM_ERROR : EXCEPTION_ACCESS_VIOLATION instead, but the debugger
> prompts the same message.

OK, C++ code you have referred to, looks quite ..., so let me suggest a bit
offending thing. What if they copy pointers to strings?

So what happens if you allocate the string passed to CTHSetText statically:

   Object_Text : Interfaces.C.Char_Array :=
       Interfaces.C.To_C ("Object");
begin
   ...
   CTHSetText (TextHelperID, Object_Text);
       -- CTHSetText remembers a pointer to Object_Text, which has to
       -- exist as long as the library may dereference it
   ...

Another suggestion. If CTHSetText actually takes a pointer to a dynamically
allocated string which will be freed later somewhere inside the library.
Then CTHSetText should be declared like this:

   procedure CTHSetText
     (Helper : System.Address; Name_Ptr : Interfaces.C.Strings.chars_ptr);
   pragma Import (C, CTHSetText, ...);

and used as:

   CTHSetText (TextHelperID, Interfaces.C.Strings.New_String ("Object"));
       -- CTHSetText takes care of the memory allocated

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de