What's the equivalent in Delphi 3 of Supports for Interfaces?
I support an application written in Delphi 3 and I would like to put in some improvements to the source code while waiting for the opportunity to upgrade it to a newer version of Delphi. One of the things I would like to use is Interfaces. I know Delphi 3 already has the concept of Interfaces but I am having trouble finding out how to do the equivalent of
if Supports(ObjectInstance, IMyInterface) then
Write your own implementation of "Supports" function. In Delphi 2009 you can use
function MySupports(const Instance: TObject; const IID: TGUID): Boolean; var Temp: IInterface; LUnknown: IUnknown; begin Result:= (Instance <> nil) and ((Instance.GetInterface(IUnknown, LUnknown) and (LUnknown.QueryInterface(IID, Temp) = 0)) or Instance.GetInterface(IID, Temp)); end;
procedure TForm4.Button3Click(Sender: TObject); var Obj: TInterfacedObject; begin Obj:= TInterfacedObject.Create; if MySupports(Obj, IUnknown) then ShowMessage('!!'); end;
Hope it will work in Delphi 3