performance of tuple-less Python?
Gordon McMillan
gmcm at hypernet.com
Mon Nov 29 13:06:33 EST 1999
François Pinard wrote:
> "Greg Wilson" <gvwilson at nevex.com> writes:
>
> > [...] the use of tuples (which I believe are conceptually
> > redundant) [...]
>
> Tuples may be used to index within dictionaries, and I find this
> feature very useful. Lists may not. I do not know the
> implementation details, but would be tempted to have the
> prejudice (:-) that using lists to index would imply some severe
> performance penalty.
I'm guessing that not being able to find something you stuck
in the dictionary qualifies as a performance penalty ;-).
To spell it out:
1) hash based on id(list_object):
d = {[1] = 'x'}
d[[1]] -> KeyError
2) hash based on value:
lst = [1]
d[lst] = 'x'
lst.append(2)
d[lst] -> KeyError
- Gordon
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