[DUG]: polymorphism problem

[Jianming Lin (ASL)]

G'Day, guys,    procedure TryMetadata(ImgType : Integer); var NGraphic: TGraphic;     GraphicClass: TGraphicClass; begin   ImgType := 1;   case ImgType of     1 :  GraphicClass := TMetaFile;     2 :  GraphicClass := TBitmap;   end;   NGraphic := GraphicClass.Create;  end;     Why constructor  of TMetafile.Create is not called instead only TObject.Create is called?          [Jianming Lin (ASL)]         This e-mail message has been scanned for Viruses and Content and cleared by MailMarshal - For more information please visit www.marshalsoftware.com