多态的作用

调用不同的子类将会产生不同的行为。

多态是在继承上实现的。

图解多态1

图解多态2

图解多态1代码

class AudioFile:    def __init__(self, filename):        if not filename.endswith(self.ext):            raise Exception("Invalid file format")        self.filename = filename        class MP3File(AudioFile):    ext = "mp3"    def play(self):        print("playing {} as mp3".format(self.filename))        class WavFile(AudioFile):    ext = "wav"    def play(self):        print("playing {} as wav".format(self.filename))        class OggFile(AudioFile):    ext = "ogg"    def play(self):        print("playing {} as ogg".format(self.filename))ogg = OggFile("myfile.ogg")ogg.play()mp3 = MP3File("myfile.mp3")mp3.play()not_an_mp3 = MP3File("myfile.ogg")not_an_mp3.play()

图解多态2代码

(参考https://www.cnblogs.com/luchuangao/p/6739557.html)

#多态：同一种事物的多种形态，动物分为人类，猪类（在定义角度）class Animal:    def run(self):        raise AttributeError('子类必须实现这个方法')  class People(Animal):    def run(self):        print('人正在走') class Pig(Animal):    def run(self):        print('pig is walking')  class Dog(Animal):    def run(self):        print('dog is running') peo1=People()pig1=Pig()d1=Dog() peo1.run()pig1.run()d1.run()

参考：本文参考学习《Python3 Object Oriented Programming》，根据自己理解改编，Dusty Phillips 著