12.2 类的派生

12.2 类的派生

1.类的查找顺序

#父类
class Foo:
    def f1(self):
        print('Foo.f1')

    def f2(self): #b
        print('Foo.f2')
        self.f1()
        
#子类
class Bar(Foo):
    def f1(self):
        print('Bar.f1')

b = Bar()
b.f2() #查找顺序：Bar()->Foo.f2()->输出Foo.f2->bar.f1()->输出Bar.f1

#输出
Foo.f2
Bar.f1

Foo.f2
Bar.f1

2. 类的派生

添加新的属性的同时还有继承父类的所有东西

#方法1：
class Animal():
    def __init__(self,height,weight):
        self.height=height
        self.weight=weight

    def jiao(self):
        print(self.__class__.__name__,'叫')
# Animal.__init__(111,185,140) #类调用传3个参数，对象调用传2个参数
        
class People(): 
    def __init__(self,name,age,height,weight):
        Animal.__init__(self,height,weight)
        self.name=name
        self.age=age
    def read(self):
        print('read')
    def sleep(self):
        print(f'self_sleep')


peo=People('coco',18,185,140)

print(peo.__dict__)

{'height': 185, 'weight': 140, 'name': 'coco', 'age': 18}

方法1总结：

• 不需要继承也可以做到
• 派生：继承父类属性的同时增加新的属性， 然后使用
• 引出方法2，方法2对方法1进行封装

#方法2：(重点)
class Animal():
    def __init__(self,height,weight):
        self.height=height
        self.weight=weight

    def jiao(self):
        print(self.__class__.__name__,'叫')
        
class People(Animal): 
    def __init__(self,name,age,height,weight):
        super().__init__(height,weight) #规定的语法super会自动调用父类的__init__,并且拿到height、weight
        self.name=name
        self.age=age
    def read(self):
        print('read')
    def sleep(self):
        print(f'self_sleep')
peo=People('coco',18,185,140)

print(peo.__dict__)

{'height': 185, 'weight': 140, 'name': 'coco', 'age': 18}

方法2总结：继承才可以

• super().init(height,weight)

尽量只继承一个父类，遵从线性继承的规则。

#继承XingXing的gender
class Animal():
    def __init__(self,height,weight):
        self.height=height
        self.weight=weight

    def jiao(self):
        print(self.__class__.__name__,'叫')

class XingXing(Animal): #继承Animal
    def __init__(self,height,weight,gender):
        super().__init__(height,weight)
        self.gender=gender
    def sleep(self):
        print('sleep')
        
class People(XingXing): #继承XingXing 
    def __init__(self,name,age,height,weight,gender):
        super().__init__(height,weight,gender) 
        self.name=name
        self.age=age
    def read(self):
        print('read')
    def sleep(self):
        print(f'self_sleep')
peo=People('coco',18,185,140,'male')

print(peo.__dict__)

#线性继承：People继承XingXing，XingXing继承Animal。

{'height': 185, 'weight': 140, 'gender': 'male', 'name': 'coco', 'age': 18}