Source code for catalyst.utils.frozen

class FrozenClass:
    """
    Class which prohibit ``__setattr__`` on existing attributes

    Examples:
        >>> class RunnerState(FrozenClass):
    """
    __isfrozen = False

    def __setattr__(self, key, value):
        if self.__isfrozen and not hasattr(self, key):
            raise TypeError("%r is a frozen class" % self)
        object.__setattr__(self, key, value)

    def _freeze(self):
        self.__isfrozen = True