Python单例模式

方法1：

class Singleton(object):
_instance = None

def __new__(cls, *args, **kwargs):
if not cls._instance:
cls._instance = super(Singleton, cls).__new__(cls, *args, **kwargs)

return cls._instance

s1 = Singleton()
s2 = Singleton()

assert id(s1) == id(s2)

方法2：

方法3：

class Borg:
__shared_state = {}

def __init__(self):
self.__dict__ = self.__shared_state