Python singleton pattern instance analysis

This article illustrates the use of the Python singleton pattern. Share with you for your reference. The details are as follows:

Methods a

import threading  

  

class Singleton(object):  

    __instance = None  

  

    __lock = threading.Lock()   # used to synchronize code  

  

    def __init__(self):  

        "disable the __init__ method"  

 

    @staticmethod  

    def getInstance():  

        if not Singleton.__instance:  

            Singleton.__lock.acquire()  

            if not Singleton.__instance:  

                Singleton.__instance = object.__new__(Singleton)  

                object.__init__(Singleton.__instance)  

            Singleton.__lock.release()  

        return Singleton.__instance

Disable the method with s/s. The object cannot be created directly.

2. Arbitration, privatization of singletons.

3.@staticmethod, staticmethod, called directly by class name.

4. S/s lock, code lock.

5. Inherit the object class, create the singleton by calling the object's s/s method, and then call the object s/s method s/s fully initialized.

6. Double check and lock, not only can achieve thread safety, but also make the performance is not greatly affected.

Method 2: use the decorator

#encoding=utf-8  

def singleton(cls):  

    instances = {}  

    def getInstance():  

        if cls not in instances:  

            instances[cls] = cls()  

        return instances[cls]  

    return getInstance  

 

@singleton  

class SingletonClass:  

    pass  

  

if __name__ == '__main__':  

    s = SingletonClass()  

    s2 = SingletonClass()  

    print s  

    print s2

Thread safety should also be added

import threading  

  

class Sing(object):  

    def __init__():  

        "disable the __init__ method"  

  

    __inst = None # make it so-called private  

  

    __lock = threading.Lock() # used to synchronize code  

 

    @staticmethod  

    def getInst():  

        Sing.__lock.acquire()  

        if not Sing.__inst:  

            Sing.__inst = object.__new__(Sing)  

            object.__init__(Sing.__inst)  

        Sing.__lock.release()  

        return Sing.__inst

I hope this article has helped you with your Python programming.