Python面向对象——多态

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