Teaching the "Polymorphism" Conception by a Sample of Game Programming

Polymorphism is a very important concept in object oriented programming,and it's also a very important method to improve the program extensibility.But it's a little bit hard for the beginner to really understand the advantage of polymorphism.This article introduces a game programming sample,which can demonstrate the advantage of polymorphism vividly.And this teaching case won awards in some teaching contests.