摘要： class A: def cost(self): print('cost a')​​class B: def cost(self): print('cost b')​​class MyAdapter:​ def __init__(self, obj): self.obj = obj​ def pay 阅读全文

摘要： class Singleton(object):​ def __new__(cls, *args, **kwargs): if not hasattr(cls, '_instance'): cls._instance = super(Singleton, cls).__new__(cls) retu 阅读全文