Why are tuples immutable?
Fredrik Lundh
fredrik at pythonware.com
Tue Dec 21 13:35:20 EST 2004
Jeff Shannon wrote:
> So show us a dictionary (i.e. hash table) implementation that can do this. You'll need to be able
> to derive the old hash from the new hash, of course, so that you can correctly associate the
> values already stored under that key. And you'll have to be able to do that without referring to
> the pre-modified object again, because dicts can't track every Python operation that might modify
> a key object. And it needs to deal properly with equivalent-but-different-ID list literals,
> because using literals (and not references stored elsewhere) is an important and common dict key
> usage.
and to temporarily refer back to the top of this thread, do all this without
any performance impact, compared to the current implementation.
</F>
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