本文实例讲述了Python使用Metaclass实现Singleton模式的方法。分享给大家供大家参考。具体实现方法如下：
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,dct)
def __init__(cls,dct):
print "Singleton init"
super(Singleton,cls).__init__(name,dct)
class Cache(object):
__Metaclass__ = Singleton
def __new__(cls,**kwargs):
print "Cache new"
return object.__new__(cls,**kwargs)
def __init__(cls,**kwargs):
print "Cache init"
def __call__(cls,**kwargs):
print "Cache call"
print Cache()
print Cache()
输出：
Singleton new Singleton init Singleton call Cache new Cache init <__main__.Cache object at 0x01CDB130> Singleton call <__main__.Cache object at 0x01CDB130>
希望本文所述对大家的Python程序设计有所帮助。