lgr

class ReadOnlyAttr:
    """ A class with the attributes that are defined on the instance
    creation and cannot be modified later. """

    # A tuple of attributes that should remain read-only
    READ_ONLY_ATTR = ('x', 'y')

    def __init__(self, *args, **kwargs):
        """ Takes a list of read-only attributes: %s """
        for attr in self.READ_ONLY_ATTR:

lgr

class AttributedDict(dict):
    """
    A class extending the standard dict so that its keys can be accessed
    as an object attributes (as long as the are strings).

    Notice: this class is not pickable, so for example an attempt to save
    its instance in Django session causes an error.
    """

    __getattr__ = dict.__getitem__