Marc Weustink het geskryf:
>
> or functions like supports() (which uses queryinterface)
Actually, that *does* work with FPC 2.4.0. See attached console application.
I used supports() and a cast to get a Corba interface reference.
It seems the compiler does some extra magic (probably with the GUID) to
identify the interface via the Supports() call - without the need for
QueryInterface.
begin
ins := TAddCommand.Create;
if Supports(ins, ICommand, cmd) then
begin
writeln('1. It worked');
cmd.Execute; // works
end;
cmd := nil;
cmd := ins as ICommand;
if Assigned(cmd) then
begin
writeln('2. It worked');
cmd.Execute; // works
end;
ins.Free;
end.
....and the the output generated...
1. It worked
TAddCommand.Execute
2. It worked
TAddCommand.Execute
Regards,
- Graeme -
--
fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal
http://opensoft.homeip.net/fpgui/
program interface_test;
{$ifdef FPC}{$mode objfpc}{$h+}{$endif}
{$ifdef mswindows}{$apptype console}{$endif}
{$Interfaces Corba}
uses
sysutils;
type
ICommand = interface
['{28D72102-D883-41A1-9585-D86B24D9C628}']
procedure Execute;
end;
TAddCommand = class(TObject, ICommand)
public
procedure Execute;
end;
procedure TAddCommand.Execute;
begin
writeln(Classname + '.Execute');
end;
var
cmd: ICommand;
ins: TAddCommand;
begin
ins := TAddCommand.Create;
if Supports(ins, ICommand, cmd) then
begin
writeln('1. It worked');
cmd.Execute;
end;
cmd := nil;
cmd := ins as ICommand;
if Assigned(cmd) then
begin
writeln('2. It worked');
cmd.Execute;
end;
ins.Free;
end.
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