Re: GPC and CodeWarrior Object Pascal

15 Apr 2006


      Peter Schorn wrote:
...
Dear all,
while porting from CodeWarrior Object Pascal to GPC I noticed the 
following differences which might be worthwhile to address in GPC.
1) Mutual recursive object type declaration
program prog1; { compile with gpc --mac-pascal prog1.pas }
type
    t1 = object
        function f: t2; { error: unknown identifier `t2' }
{ above works in CodeWarrior Object Pascal as objects are always 
references }
    end;
t2 = object
        function g: t1;
    end;
function t1.f: t2; begin f := nil; end;
function t2.g: t1; begin g := nil; end;
begin
end.
As a workaround this can be solved by introducing a common super class 
and subsequent casting.
The object can be declared forward (also see the mailing list archives)

{$mac-objects}
program prog1;
type
     t2 = object; forward;
     t1 = object
         function f: t2;
     end;
     t2 = object
         function g: t1;
     end;

function t1.f: t2; begin f := nil; end;
function t2.g: t1; begin g := nil; end;
begin
end.

Regards,

Adriaan van Os