Re: Access to data indirection (newbie)

[axtens <Bruce.Axtens@gmail.com>]

On Nov 28, 7:20 am, Simon Wright <simon.j.wri...@mac.com> wrote:
> Martin Krischik <krisc...@users.sourceforge.net> writes:

Well, anyway, I figured out a solution to my question, after reading
the "Summary of Operations on Access Values" in Feldman's "Software
Construction and Data Structures with Ada 95."

For ages I couldn't figure out why I felt a prompting to pick this
book up at a booksale in the local library. Now I think I know what
God was up to.

Nevertheless, thanks to both of you for adding your two bob's worth to
the mix. What I've ended up with, at least this far in, is:

VB6:
  Declare Function handlepointer Lib "release\api.dll" (ByVal x As
Long) As Long
  Dim i As Long
  i = 1001
  Debug.Print VarPtr(i)
  Debug.Print handlepointer(VarPtr(i))

Output:
 1309644
 1001

Api.ads (part of):
   function HandlePointer (
       Left : in     Win32.LONG)
   return Win32.LONG;
   ...
   pragma Export (DLL, HandlePointer );

Api.adb (part of):
   function HandlePointer (
         Left : in     Win32.LONG)
     return Win32.LONG is

      type LongRec is
         record
            L : Win32.LONG;
         end record;

      type PointerToLongRec is access LongRec;

      function Conv is
      new Unchecked_Conversion (Win32.LONG, PointerToLongRec );

      PLongRec : PointerToLongRec;
   begin
      PLongRec := Conv(Left);
      return PLongRec.All.L;
   end HandlePointer;

Kind regards,
Bruce.