Un-borg-ify AppCache

__all__ = ('get_apps', 'get_app', 'get_models', 'get_model', 'register_models',

        'load_app', 'app_cache_ready')

class AppCache(object):

    """

    A cache that stores installed applications and their models. Used to

    provide reverse-relations and for app introspection (e.g. admin).

    """

    # Use the Borg pattern to share state between all instances. Details at

    # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531.

    __shared_state = dict(

        # Keys of app_store are the model modules for each application.

        app_store = SortedDict(),

    def __init__(self):

        # Keys of app_store are the model modules for each application.

        self.app_store = SortedDict()

        # Mapping of installed app_labels to model modules for that app.

        app_labels = {},

        self.app_labels = {}

        # Mapping of app_labels to a dictionary of model names to model code.

        # May contain apps that are not installed.

        app_models = SortedDict(),

        self.app_models = SortedDict()

        # Mapping of app_labels to errors raised when trying to import the app.

        app_errors = {},

        self.app_errors = {}

        # -- Everything below here is only used when populating the cache --

        loaded = False,

        handled = {},

        postponed = [],

        nesting_level = 0,

        _get_models_cache = {},

    )

    def __init__(self):

        self.__dict__ = self.__shared_state

        self.loaded = False

        self.handled = {}

        self.postponed = []

        self.nesting_level = 0

        self._get_models_cache = {}

    def _populate(self):

        """