python的单例开发模式

# 使用类方法实现单例
class MyMeta(type):
    __instance = None
    def __init__(self,x,y):
        self.x = x
        self.y = y

    @classmethod
    def from_conf(cls,*args,**kwargs):
        if cls.__instance is None:
            cls.__instance=cls(*args,**kwargs)
        return cls.__instance

# 使用__new__方法实现单例
class Example:
    __instance = None
    def __init__(self,x,y):
        self.x = x
        self.y = y
    
    def __new__(cls, *args, **kwargs):
        if cls.__instance is None:
            cls.__instance = object.__new__(cls):
        return cls.__instance