class Singleton(type):
def __call__(cls, *args, **kwargs):
print "Singleton call"
if not hasattr(cls, 'instance'):
cls.instance = super(Singleton, cls).__call__(*args, **kwargs)
return cls.instance
def __new__(cls, name, bases, dct):
print "Singleton new"
return type.__new__(cls, name, bases, dct)
def __init__(cls, name, bases, dct):
print "Singleton init"
super(Singleton, cls).__init__(name, bases, dct)
class Cache(object):
__metaclass__ = Singleton
def __new__(cls, *args, **kwargs):
print "Cache new"
return object.__new__(cls, *args, **kwargs)
def __init__(cls, *args, **kwargs):
print "Cache init"
def __call__(cls, *args, **kwargs):
print "Cache call"
print Cache()
print Cache()
输出：
Singleton newSingleton initSingleton callCache newCache init<__main__.Cache object at 0x01CDB130>Singleton call<__main__.Cache object at 0x01CDB130>
转载于:https://www.cnblogs.com/tuzkee/archive/2013/02/05/2892547.html
相关资源：数据结构—成绩单生成器
