Pyhon进阶9---类的继承

类的继承

基本概念

SRE实战 互联网时代守护先锋，助力企业售后服务体系运筹帷幄！一键直达领取阿里云限量特价优惠。

定义

格式如下

 

继承中的访问控制

class Animal:
    __CNOUT = 0
    HEIGHT = 0

    def __init__(self,age,weight,height):
        self.__CNOUT += 1
        self.age = age
        self.__weight = weight
        self.HEIGHT = height

    def eat(self):
        print('{} eat'.format(self.__class__.__name__))

    def __getweight(self):
        print(self.__weight)

    @classmethod
    def showcount1(cls):
        print(cls.__CNOUT)

    @classmethod
    def __showcount2(cls):
        print(cls.__CNOUT)

class Cat(Animal):
    NAME = 'CAT'

c = Cat(3,5,15)
c.eat()
c.showcount1()#注意此处的cls.__COUNT仍为0

print(c.NAME)
print(c.__dict__)#{'_Animal__CNOUT': 1, 'age': 3, '_Animal__weight': 5, 'HEIGHT': 15}
print(Cat.__dict__)#{'__module__': '__main__', 'NAME': 'CAT', '__doc__': None}
print(Animal.__dict__)

 

方法的重写、覆盖override

class Animal:
    def shout(self):
        print('Animal shout')

class Cat(Animal):
    #覆盖父类的方法
    def shout(self):
        print('miao')
    #覆盖自身的方法，显示调用了父类的方法
    def shout(self):
        print(super(Cat, self))
        print(super(Cat,self))
        super().shout()

a = Animal()
a.shout()
c =Cat()
c.shout()

#输出结果：
# Animal shout
# <super: <class 'Cat'>, <Cat object>>
# <super: <class 'Cat'>, <Cat object>>
# Animal shout

 

class Animal:
    @classmethod
    def class_method(cls):
        print('class_method_animal')

    @staticmethod
    def static_method():
        print('static_method_animal')

class Cat(Animal):
    @classmethod
    def class_method(cls):
        print('class_method_cat')

    @staticmethod
    def static_method():
        print('static_method_cat')

c = Cat()
c.class_method()
c.static_method()
#输出结果：
# class_method_cat
# static_method_cat

继承中的初始化

示例1

class A:
    def __init__(self):
        self.a1 = 'a1'
        self.__a2 = 's2'
        print('A init')

class B(A):
    pass
b = B()
print(b.__dict__)       #{'a1': 'a1', '_A__a2': 's2'}

示例2

class A:
    def __init__(self):
        self.a1 = 'a1'
        self.__a2 = 's2'
        print('A init')

class B(A):
    def __init__(self):
        self.b1 = 'b1'
        print('B init')
b = B()
print(b.__dict__)    #{'b1': 'b1'}

class A:
    def __init__(self):
        self.a1 = 'a1'
        self.__a2 = 's2'
        print('A init')

class B(A):
    def __init__(self):
        # A.__init__(self)
        # super(B,self).__init__()
        super().__init__()
        self.b1 = 'b1'
        print('B init')
b = B()
print(b.__dict__)   #{'a1': 'a1', '_A__a2': 's2', 'b1': 'b1'}

如何正确初始化

 

class Animal:
    def __init__(self,age):
        print('Animal init')
        self.age =age

    def show(self):
        print(self.age)

class Cat(Animal):
    def __init__(self,age,weight):
        super().__init__(age)#c.show()结果为11
        print('Cat init')
        self.age = age + 1
        self.weight = weight
        # super().__init__(age)#c.show()结果为10
c = Cat(10,5)
c.show()

class Animal:
    def __init__(self,age):
        print('Animal init')
        self.__age =age

    def show(self):
        print(self.__age)

class Cat(Animal):
    def __init__(self,age,weight):
        super().__init__(age)
        print('Cat init')
        self.__age = age + 1
        self.__weight = weight
c = Cat(10,5)
c.show()
print(c.__dict__)#{'_Animal__age': 10, '_Cat__age': 11, '_Cat__weight': 5}

 

 

Python不同版本的类

多继承

 

多继承弊端

Python多继承实现

class ClassName(基类列表):
    类体

 

扫码关注我们

微信号：SRE实战

拒绝背锅 运筹帷幄