Python design patterns
From wikinotes
NOTE:
This page is just implementations.
See more general notes/best-practices in Algorithms: patterns .
Singleton
A singleton is a class that once instantiated always returns the same instance. This is useful for bundling global variables, or logs are a classic use.
class SomeSingleton( object ): __instance__ = None def __new__(self, *args,**kwargs): if SomeSingleton.__instance__ is None: SomeSingleton.__instance__ = object.__new__(self) return SomeSingleton.__instance__