__new__()

1. 实现一个简单的单例模式

class Test:
    a = None
    def __new__(cls,*args, **kwargs):
        if cls.a ==None:
            cls.a = super().__new__(cls)
        return cls.a

player = Test()
player2 = Test()
player3 = Test()
player4 = Test()

print(player)
print(player2)
print(player3)
print(player4)
>>>
<__main__.Test object at 0x01ED1A30>
<__main__.Test object at 0x01ED1A30>
<__main__.Test object at 0x01ED1A30>
<__main__.Test object at 0x01ED1A30>