In http://mail.python.org/pipermail/python-dev/2012-February/117113.html Victor Stinner posted:
An immutable mapping can be implemented using frozendict::
class immutabledict(frozendict): def __new__(cls, *args, **kw): # ensure that all values are immutable for key, value in itertools.chain(args, kw.items()): if not isinstance(value, (int, float, complex, str, bytes)): hash(value) # frozendict ensures that all keys are immutable return frozendict.__new__(cls, *args, **kw)
What is the purpose of this? Is it just a hashable frozendict? If it is for security (as some other messages suggest), then I don't think it really helps. class Proxy: def __eq__(self, other): return self.value == other def __hash__(self): return hash(self.value) An instance of Proxy is hashable, and the hash is not object.hash, but it is still mutable. You're welcome to call that buggy, but a secure sandbox will have to deal with much worse. -jJ -- If there are still threading problems with my replies, please email me with details, so that I can try to resolve them. -jJ