[lazarus] narrowing down the Dispatch problem

[michael at tfdec1.fys.kuleuven.ac.be]

On Sat, 10 Jul 1999, Michael A. Hess wrote:

> Peter,
> 
> I have narrowed it down to the following line. In Dispatch the line that
> is determining the number of messages in the table is causing the error.
> Let's put it this way that line is were it blows up in xxgdb.  :-)
> 
>   count:=pdword((pdword(...........
> 
> This is where it stops in the debugger.

If you got this far, you should have noticed that the vmt was already the
vmt of TObject - which has no messages, and hence is a special case.

I added a check to see if there are messages for that class - now the
follwing runs fine:

program testdisp;

{$mode objfpc}

type TMyObject = Class(TObject)
       Procedure Message1(Var Msg); message 1;
       Procedure Message2(Var Msg); message 2;
//       Procedure Message3(Var Msg); message 3;
     end;

Procedure TMYObject.Message1(Var Msg);
begin
  Writeln ('Got message : ',DWord(Msg));
end;

Procedure TMyObject.Message2(Var Msg);
begin
  Writeln ('Got message : ',DWord(Msg));
end;

{
Procedure TMyObJect.Message3(Var Msg); message 3;
begin
  Writeln ('Got message : ',DWord(Msg));
end;
}
Var MyObject : TMyObject;
    Msg : Longint;
begin
  MyObject:=TMyObject.Create;
  // Run until 3, so a non-registered message is sent.
  For Msg:=1 to 3 do 
    MyObject.Dispatch(Msg);
end.

I've committed this in the RTL.

> 
> Could this be related to the same reason that we can't add more than 2
> messages to a class definition?

No, because that is a compiler problem, not an RTL problem. So that still
needs to be solved.

Michael.