Python 单例(singleton) 方式比拼

singleton.py

#!/usr/bin/env python
# encoding: utf-8

class Singleton(type):
    def __init__(cls, name, bases, dict):
        super(Singleton, cls).__init__(name, bases, dict)
        cls.instance = None 

    def __call__(cls,*args,**kw):
        if cls.instance is None:
            cls.instance = super(Singleton, cls).__call__(*args, **kw)
        return cls.instance

class MetaSingleton(object):

    __metaclass__ = Singleton
    counter = 1

    def get(self):
        self.counter += 1
        return self.counter


class ModuleSingleton(object):
    
    counter = 1
    def get(self):
        self.counter += 1
        return self.counter

m = ModuleSingleton()

def singleton(cls):
    instances = {}
    def getinstance():
        if cls not in instances:
            instances[cls] = cls()
        return instances[cls]
    return getinstance

@singleton
class DecoratorClass:

    counter = 1

    def get(self):
        self.counter += 1
        return self.counter

test_result.log

In [3]: %%timeit
singleton_test.m.get()
1000000 loops, best of 3: 367 ns per loop

In [4]: %%timeit
singleton_test.DecoratorClass().get()
1000000 loops, best of 3: 715 ns per loop

In [8]: %%timeit                             
singleton_test.MetaSingleton().get()
1000000 loops, best of 3: 727 ns per loop