immutable_class.py

class ImmutableClass(type):
    def __new__(mcs, class_name, bases, class_dict):
        instance = type.__new__(mcs, class_name, bases, class_dict)
        instance.__setattr__ = ImmutableClass._setattr_impl
        instance.__delattr__ = ImmutableClass._delattr_impl
        return instance

    def __call__(cls, *args, **kwargs):
        obj = type.__call__(cls, *args, **kwargs)
        obj.__immutable__ = True
        return obj

    @staticmethod
    def _setattr_impl(self, attr, value):
        if '__immutable__' in self.__dict__ and self.__immutable__:
            raise AttributeError("Set not supported! '{self}' is immutable".format(self=self))
        else:
            object.__setattr__(self, attr, value)

    @staticmethod
    def _delattr_impl(self, attr):
        raise AttributeError("Delete not supported! '{self}' is immutable".format(self=self))