Python single-instance mode

1. Using the __new__ method

class Singleton:     def __new__ (CLS, *args, * *Kwargs)        : if  not ' _instance ' ):            = Super (). __new__ (CLS, *args, * *Kwargs        ) return cls._instance class MyClass (Singleton):     Pass

__new__ contact with __init__:

__new__ is called before the instance is created, because its task is to create an instance and then return to that instance, which is a static method.

__init__ is called when the instance object is created, and then sets some initial values for the object properties.

2. Using adorners

def Singleton (CLS):     = {}    def getinstance (*args, * *Kwargs)        :if not Instances.get (CLS):            = CLS (*args, * *Kwargs        )return  Instances[cls]     return  Getinstance@singletonclass  MyClass:    Pass 

3. Use Import

# myclass.py class MyClass:     Pass  = MyClass ()# from MyClass import obj

Python single-instance mode