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 than reading my 'explanations'. thank you.

setCtrlState([ memo1, edit1, button1], False);

_

procedure setCtrlState(objs: array of TObject; bState: boolean = True);
var
  obj: TObject;
  ct: TClass;
begin
  for obj in objs do
  begin
    ct := obj.ClassType;


    if (ct = TMemo) or (ct = TEdit) then
      ct( obj ).ReadOnly := not bState;        // error here :(

    if ct = TButton then
      ct( obj ).Enabled:= bState;        // and here :(

  end;
end;

Answer 1

You must explicitly cast object to some class. This should work:

 procedure setCtrlState(objs: array of TObject; bState: boolean = True);
 var
   obj: TObject;
   ct: TClass;
 begin
  for obj in objs do
  begin
    ct := obj.ClassType;

    if ct = TMemo then
      TMemo(obj).ReadOnly := not bState
    else if ct = TEdit then
      TEdit(obj).ReadOnly := not bState
    else if ct = TButton then
      TButton(obj).Enabled := bState;
  end;
end;

This can be shortened using "is" operator - no need for ct variable:

 procedure setCtrlState(objs: array of TObject; bState: boolean = True);
 var
   obj: TObject;
 begin
   for obj in objs do
   begin
     if obj is TMemo then
       TMemo(obj).ReadOnly := not bState
     else if obj is TEdit then
       TEdit(obj).ReadOnly := not bState
     else if obj is TButton then
       TButton(obj).Enabled := bState;
   end;
 end;