Python编程基础 课件 7.3 继承与多态

Python编程基础项目七面向对象的编程7.3继承与多态目录7.3.1继承7.3.2多态Python编程基础7.3.1继承Python编程基础继承Python编程基础一个问题父类子类defskill(self):print(“我会做馒头”)defskill(self):print(“我会做蛋糕”)继承Python编程基础又一个问题重写又叫覆盖，老手艺已经不在了继承Python编程基础重写后访问父类方法可以通过“父类名.父类方法”调用调用前，使用父类__init__()初始化继承Python编程基础继承中的selfself总是指向发起方法调用的那个实例Father.skill（self）selfskill（self）继承与派生Python编程基础继承的概念减少重复代码代码逻辑清晰继承与派生PersonnamegenderagenamegenderagemajordeptStudentPython编程基础父类与子类继承与派生Python编程基础派生-定义父类classPerson：def__init__(self,name,gender,age):=nameself.gender=genderself.age=agedefintroduce(self):returnf’Iam{},mygenderis{self.gender}andIam{self.age}.’形参，属性名都要做到“望文知义”继承与派生Python编程基础派生-派生子类classStudent（Person)：def__init__(self,name,gender,age,major,detp):Person.__init__(self,name,gender,age)self.major=majorself.dept=deptdefintroduce(self):returnf’Iam{},mygenderis{self.gender}andIam{self.age},mymajor is{self.major,andIamin{self.dept}.’继承与派生Python编程基础验证p1=Person(“James”,”male”,50)s1=Student(“Jack”,”male”,22,”IoT”,”NC”)print(roduce())print(roduce())IamJames,mygenderismale,andIam50IamJack,mygenderismale,andIam22,mymajorisIoT,IamNC多继承Python编程基础多继承的概念python允许一个类同时从多个父类继承属性和方法，这就是多继承子类父类做馒头做包子做蛋糕多继承Python编程基础继承谁？多继承Python编程基础方法继承两个父类中都有skill()函数那该如何继承呢？MRO（MethodResolutionOrder）7.3.2多态Python编程基础多态Python编程基础多态的概念多种形态，同一事物在不同场景下有不同形态一个函数，输入参数不同实现不同的效果printf(f’Helloworld!’)；printf(f’val={val}’)；Helloworld!val=10多态Python编程基础实现多态的条件1）继承2）函数重写3）父类引用指向子类对象子类重写父类函数子类对象传递给父类对象调用者定义父类、子类多态Python编程基础多态-类的继承AnimalDogCatclassAnimal：defsound(self):print(“helloanimals”)classDog(Animal)：passclassCat(Animal)：pass多态Python编程基础多态-函数重写AnimalDogCatclassAnimal：defsound(self):print(“helloanimals”)classDog(Animal)：defsound(self):print(“汪汪汪”)classCat(Animal)：defsound(self):print(“喵喵喵”)多态Python编程基础多态-父类引用指向子类对象AnimalDogCatd=Dog()c=Cat()dcdefmakeSound(an:An