关于面向对象多态的问题?
彩练当空 2011-11-08 09:37:41 type
TFigure=class
procedure Draw;
end;
TRectangle=class(TFigure)
procedure Draw;
end;
var
Figure:TFigure;
Rectangle:TRectangle;
begin
Figure:=TFigure.create;
Figure.Draw; //调用的是TFigure.Draw;
Figure.Destroy;
Figure:=TRectangle.create;
Figure.Draw; //调用的是TFigure.Draw,为什么?;
TRectangle(Figure).Draw; //调用的是TRectangle.Draw
Figure.Destroy;
Rectangle:=Trectangle.Create; //调用的是TRectangle.Draw
Rectangle.Draw;
Rectangle.Destroy;