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

You need to cast the ct object to a TMemo/TEdit/TButton before you can set properties on the object.

The line where you're getting errors are erroring because ct is still a TClass, not a TButton/etc. If you cast to a TButton, then you'll be able to set enabled to true.

I recommend reading up on casting in Delphi. Personally, I would recommend using the as/is operators instead of using ClassType, as well. The code will be simpler in that case, and much more understandable.

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Personally, I would write this more like:

procedure setCtrlState(objs: array of TObject; bState: boolean = True);
var
  obj: TObject;
begin
  for obj in objs do
  begin
    // I believe these could be merged by using an ancestor of TMemo+TEdit (TControl?)
    // but I don't have a good delphi reference handy
    if (obj is TMemo) then
        TMemo(obj).ReadOnly := not bState;

    if (obj is TEdit) then
        TEdit(obj).ReadOnly := not bState;

    if (obj is TButton) then
        TButton(obj).Enabled := bState;
  end;
end;