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'>]