inheritance - Delphi: How to call inherited inherited ancestor on a virtual method?

Question

I'm overriding a virtual method, and I want to call inherited. But I don't want to call the immediate ancestor, I want to call the one before.

TObject
   TDatabaseObject
      TADODatabaseObject <---call this guy
         TCustomer        <---skip this guy
            TVIP           <---from this guy

I tried casting myself as the ancestor, and call the method on that, but it led to recursive stack overflow:

procedure TVip.SetProperties(doc: IXMLDOMDocument);
begin
   TADODatabaseObject(Self).SetProperties(doc); //skip over TCustomer ancestor
   ...
end;

i tried adding the inherited keyword, but that doesn't compile:

procedure TVip.SetProperties(doc: IXMLDOMDocument);
begin
   inherited TADODatabaseObject(Self).SetProperties(doc); //skip over TCustomer ancestor
   ...
end;

Possible?

Answer 1

You can do it using a hack of obtaining static address of virtual method:

type
  TBase = class
    procedure Foo; virtual;
  end;

  TAnsestor = class(TBase)
    procedure Foo; override;
  end;

  TChild = class(TAnsestor)
    procedure Foo; override;
    procedure BaseFoo;
  end;

procedure TBase.Foo;
begin
  ShowMessage('TBase');
end;

procedure TAnsestor.Foo;
begin
  ShowMessage('TAnsestor');
end;

procedure TChild.Foo;
begin
  ShowMessage('TChild');
end;

type
  TFoo = procedure of object;

procedure TChild.BaseFoo;
var
  Proc: TFoo;

begin
  TMethod(Proc).Code := @TBase.Foo; // Static address
  TMethod(Proc).Data := Self;
  Proc();
end;

procedure TForm4.Button1Click(Sender: TObject);
var
  Obj: TChild;
  Proc: TFoo;

begin
  Obj:= TChild.Create;
  Obj.BaseFoo;
// or else
  TMethod(Proc).Code := @TBase.Foo; // Static address
  TMethod(Proc).Data := Obj;
  Proc();

  Obj.Free;
end;