python不可变字典

immutabledict.py

class ImmutableDict(dict):

    _HASH = None

    def __new__(cls, *args, **kwargs):
        ImmutableDict._HASH = hash(frozenset(args[0].items()))
        return super(ImmutableDict, cls).__new__(cls, args)

    def __hash__(self):
        return self._HASH

    def _readonly(self, *args, **kwards):
        raise TypeError("Cannot modify Immutable Instance")

    __delattr__ = __setattr__ = __setitem__ = pop = update = setdefault = clear = popitem = _readonly