Python Singleton mode and Python Mode

Python Singleton mode and Python Mode

Method 1

 

Python code

1. Import threading
3. Class Singleton (object ):
4. _ Instance = None
6. _ Lock = threading. Lock () # used to synchronize code
8. Def _ init _ (self ):
9. "Disable the _ init _ method"
10.  
11. @ Staticmethod
12. Def getInstance ():
13. If not Singleton. _ instance:
14. Singleton. _ lock. acquire ()
15. If not Singleton. _ instance:
16. Singleton. _ instance = object. _ new _ (Singleton)
17. Object. _ init _ (Singleton. _ instance)
18. Singleton. _ lock. release ()
19. Return Singleton. _ instance

1. Disable the _ init _ method. You cannot directly create an object.

2. _ instance: the singleton object is private.

3. @ staticmethod: static method, called directly by class name.

4. _ lock: code lock.

5. inherit from the object class, create a singleton object by calling the _ new _ method of the object, and call the complete initialization of the _ init _ method of the object.

6. Double check and locking can not only achieve thread security, but also ensure high performance.

 

Method 2: decorator

 

Python code

1. # Encoding = UTF-8
2. Def singleton (cls ):
3. Instances = {}
4. Def getInstance ():
5. If cls not in instances:
6. Instances [cls] = cls ()
7. Return instances [cls]
8. Return getInstance
9.  
10. @ Singleton
11. Class SingletonClass:
12. Pass
14. If _ name _ = '_ main __':
15. S = SingletonClass ()
16. S2 = SingletonClass ()
17. Print s
18. Print s2

 

Thread security should also be added

 

 

Appendix: High Performance

 

Python code

1. Import threading
3. Class Sing (object ):
4. Def _ init __():
5. "Disable the _ init _ method"
7. _ Inst = None # make it so-called private
9. _ Lock = threading. Lock () # used to synchronize code
10.  
11. @ Staticmethod
12. Def getInst ():
13. Sing. _ lock. acquire ()
14. If not Sing. _ inst:
15. Sing. _ inst = object. _ new _ (Sing)
16. Object. _ init _ (Sing. _ inst)
17. Sing. _ lock. release ()
18. Return Sing. _ inst