Source code for spec2nexus.singletons

"""
singletons: Python 2 and 3 Compatible Version

:see: http://stackoverflow.com/questions/6760685/creating-a-singleton-in-python

USAGE::

    class Logger(Singleton):
        pass

"""


class _Singleton(type):

    """A metaclass that creates a Singleton base class when called."""

    _instances = {}

    def __call__(self, *args, **kwargs):
        if self not in self._instances:
            self._instances[self] = super(_Singleton, self).__call__(
                *args, **kwargs
            )
        return self._instances[self]


class Singleton(_Singleton("SingletonMeta", (object,), {})):
    """Public interface"""