cast TObject using his ClassType?

Question

how can i make my code to work ? :) i`ve tried to formulate this question but after several failed attempts i think you guys will spot the problem faster looking at the code

Answer 1

There is no need to cast to TMemo and TEdit separately, as they are both descendants from common parent class, which have ReadOnly property:

procedure TForm1.FormCreate(Sender: TObject);

  procedure P(const Obj: TComponent);
  begin
    if Obj is TCustomEdit then
      TCustomEdit(Obj).ReadOnly := True;
  end;

begin
  P(Memo1);
  P(Edit1);
end;