program Project3;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils;

type
   IMyInterface = interface
   ['{88DDD9A5-F4BC-47B9-9240-31B1C986F230}']
      procedure doSomething();
   end;

   TMyClass = class(TInterfacedObject, IMyInterface)
      public
            constructor Create();
         procedure doSomething();
   end;

procedure justSupportsThings();
var
   myObject:   TObject;
   myIntf:      IMyInterface;
   castSuccessful:   Boolean;
begin
   myObject := TMyClass.Create();
   castSuccessful := Supports(myObject, IInterface, myIntf);
   if castSuccessful then myIntf.doSomething();
end;

constructor TMyClass.Create();
begin
   _AddRef(); // Damit mich das Supports(..) nicht abräumt
end;

procedure TMyClass.doSomething;
begin
   // nop
end;

begin
  try
   justSupportsThings();
  except
   on E: Exception do
     Writeln(E.ClassName, ': ', E.Message);
  end;
  readln;
end.