Wie Klassen (keine Instanz!) als Variable übergegben?

[freak4fun]

function TFoo.IndexOfClass(AClass: TOberklasse): Integer; Das sollte gehen! Wie heißt der genaue Fehler?

Delphi-Quellcode:

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TParent = class

  end;

  TChild = class(TParent)

  end;

  TTest = class(TChild)

  end;

  TForm2 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
    procedure test(AClass: TParent); 
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
var
  ltest: TTest;
begin
  test(ltest);
end;

procedure TForm2.test(AClass: TParent);
begin
  ShowMessage('-.-');
end;

end.