"procedure of object" problems...

[Lerry]

Hi! I am new to FreePascal/Lazarus (being experienced Delphi programmer, however). Need your help. Maybe this is not the right place for this question, but… I found pretty interesting (and annoying) thing that I cannot explain. Maybe you can help. Take a look at the code:

Code: [Select]

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  ...;

type

  { TForm1 }

  TForm1 = class(TForm)
    ...
  private
    procedure AMethod();
  public
  end;

...

implementation

{ TForm1 }

type
  TMethod = procedure of object;

procedure TForm1.Button1Click(Sender: TObject);
var
  m: TMethod;
begin
  m:= AMethod;  // Get compile time error here!
end;

procedure TForm1.AMethod();
begin

end;

...

end.

I’ve declared TMethod type (procedure of object), and created a method AMethod() that takes no parameters. When I declare a variable of type TMethod and try to assign to that variable my AMethod(), compiler says: “Incompatible types: got “untyped” expected “<procedure variable type of procedure of object; Register>””. Who knows what this is???

Thanks.

[JanH]

declare your proc-Type like this:

type
  TMethod = procedure () of object;

[JanH]

edit:

and set m like this:

m := @AMethod;

[Lerry]

Oh! Thanks! So the answer is so simple! I was surprised when got that error. FPC behaves in a different way than Delphi compiler does...

[RudieD]

If you don't want to use the @ you can always put {$MODE DELPHI} just after the unit name;

[kegge13]

If you don't want to use the @ you can always put {$MODE DELPHI} just after the unit name;

Thanks for this excellent tip.