本文共 987 字，大约阅读时间需要 3 分钟。

1、使用装饰器

def singleton(cls): _instance = {} def _singleton(*args, **kwargs): if cls not in _instance: _instance[cls] = cls(*args, **kwargs) return _instance[cls] return _singleton@singletonclass A(object): def __init__(self, x): self.x = x assert id(A(1)) == id(A(2)) 2、类内实现，通过定义get_singleton函数+非线程安全

class Singleton(object): def __init__(self,*args,**kwargs): pass @classmethod def get_instance(cls, *args, **kwargs): if not hasattr(Singleton, '_instance'): Singleton._instance = Singleton(*args, **kwargs) return Singleton._instance

3、类内实现，通过定义__new__函数+线程安全

import threadingclass Singleton(object): _instance_lock = threading.Lock() def __init__(self, *args, **kwargs): pass def __new__(cls, *args, **kwargs): if not hasattr(cls, '_instance'): with Singleton._instance_lock: if not hasattr(cls, '_instance'): Singleton._instance = super().__new__(cls) return Singleton._instancedef task(arg): obj = Singleton()for i in range(10): t = threading.Thread(target=task, args=[i, ]) t.start()

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