55 lines
1.0 KiB
Python
55 lines
1.0 KiB
Python
"""
|
|
多重继承 - 一个类有两个或者两个以上的父类
|
|
MRO - 方法解析顺序 - Method Resolution Order
|
|
当出现菱形继承（钻石继承）的时候，子类到底继承哪个父类的方法
|
|
Python 2.x - 深度优先搜索
|
|
Python 3.x - C3算法 - 类似于广度优先搜索
|
|
"""
|
|
class A():
|
|
|
|
def say_hello(self):
|
|
print('Hello, A')
|
|
|
|
|
|
class B(A):
|
|
pass
|
|
|
|
|
|
class C(A):
|
|
|
|
def say_hello(self):
|
|
print('Hello, C')
|
|
|
|
|
|
class D(B, C):
|
|
pass
|
|
|
|
|
|
class SetOnceMappingMixin():
|
|
"""自定义混入类"""
|
|
__slots__ = ()
|
|
|
|
def __setitem__(self, key, value):
|
|
if key in self:
|
|
raise KeyError(str(key) + ' already set')
|
|
return super().__setitem__(key, value)
|
|
|
|
|
|
class SetOnceDict(SetOnceMappingMixin, dict):
|
|
"""自定义字典"""
|
|
pass
|
|
|
|
|
|
def main():
|
|
print(D.mro())
|
|
# print(D.__mro__)
|
|
D().say_hello()
|
|
print(SetOnceDict.__mro__)
|
|
my_dict= SetOnceDict()
|
|
my_dict['username'] = 'jackfrued'
|
|
my_dict['username'] = 'hellokitty'
|
|
|
|
|
|
if __name__ == '__main__':
|
|
main()
|