Elegant Python-Singleton mode strum

Method One: adorners

With the "adorner will only perform once" feature

1 defSingleton (CLS):2instances = []#Why is this not direct to none, because the intrinsic function cannot access the non-container variables of the external function3     defgetinstance (*args, * *Kwargs):4         if  notinstances:5Instances.append (CLS (*args, * *Kwargs))6         returnInstances[0]7     returngetinstance8 9 @singletonTen classFoo: OneA = 1 A  -F1 =Foo () -F2 =Foo () the PrintID (F1), ID (F2)

Method Two: base class

Use "class variable to be unique to all objects", i.e. cls._instance

1 classSingleton (object):2     def __new__(CLS, *args, * *Kwargs):3         if  notHasattr (CLS,'_instance'):4Cls._instance = object.__new__(CLS, *args, * *Kwargs)5         returncls._instance6 7 classFoo (Singleton):8A = 1

Method Three: Metaclass

Use "class variable to be unique to all objects", i.e. cls._instance

1 classSingleton (type):2     def __call__(CLS, *args, * *Kwargs):3         if  notHasattr (CLS,'_instance'):4Cls._instance = Super (Singleton, CLS).__call__(*args, * *Kwargs)5         returncls._instance6 7 classFoo ():8     __metaclass__= Singleton

Method Four: Borg mode

Use "class variable to be unique to all objects", i.e. __share_state

1 class Foo: 2    __share_state = {}3    def__init__(self):4 Self        . __dict__ = self. __share_state

Method Five: Using Import

Use "module will only be import once"

1 # in the file Mysingleton 2 class Foo (object): 3      Pass 4 5 f = Foo ()

Then in other modules, from Mysingleton import F
Take F directly as a singleton object to use

Transferred from: http://blog.csdn.net/handsomekang/article/details/46672047

Elegant Python-Singleton mode strum