[EMAIL PROTECTED] wrote:
> Andre Meyer:
>> What is the preferred pythonic way of implementing singleton elegantly?
>
> Maybe to just use a module.
>
> Bye,
> bearophile
>
Here is some sample code for both singleton classes and named classes
that I use:
> class Singleton(type):
> """
> This class will allow only one instance of a type
> regardless of the initialization arguments.
> """
> def __init__(self, *args, **kwargs):
> """
> This is done when the class is defined.
> """
> type.__init__(self, *args, **kwargs)
> self._instance = None
>
> def __call__(self, *args, **kwargs):
> """
> This is called when the class is instantiated.
> """
> if not self._instance : self._instance =
> type.__call__(self,*args,**kwargs)
> return self._instance
>
> class namedSingleton(type):
> """
> This class will allow a different singleton per initialization
> argument list. This implementation does not take into account
> variations in the keyword args.
> """
> def __init__(self, *args, **kwargs):
> """
> This is executed when the class is first defined.
> """
> type.__init__(self, *args, **kwargs)
> self._instances = {}
>
> def __call__(self, *args, **kwargs):
> """
> This is called when the class is instantiated.
> """
> if not args in self._instances:
> self._instances[args] = type.__call__(self, *args,**kwargs )
> return self._instances[args]
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