Python第十七天 抽象类

 from abc import ABCMeta, abstractmethod

 class A(metaclass=ABCMeta):  称 A 为抽象类
     @abstractmethod
     def test(self):pass      test 为抽象方法, 必须由继承的子类实现具体功能

 class B(A):
     pass

 B()   只要创建类  B 的 对象, 就会报错

TypeError: Can't instantiate abstract class B with abstract methods test

python3,以后,新式类, 多继承,方法的查找顺序,  广度优先算法

 class A:
     def test(self):
         print('in A')

 class B(A):
     def test(self):
         print('in B')
         super().test()

 class C(A):
     def test(self):
         print('in C')
         super().test()

 class D(B):
     def test(self):
         print('in D')
         super().test()

 class E(C):
     def test(self):
         print('in E')
         super().test()

 class F(D, E):
     def test(self):
         print('in F')
         super().test()

 F().test()

 print(F.mro())

执行结果

in F
in D
in B
in E
in C
in A
[<class '__main__.F'>, <class '__main__.D'>, <class '__main__.B'>, <class '__main__.E'>, <class '__main__.C'>, <class '__main__.A'>, <class 'object'>]