[Python-Dev] Comparison speed

[Aahz Maruch]

Tim Peters wrote:
> 
> If the time machine batteries can hold a full charge, you may want
> to go back and add Py_CMP as a seventh possible desired-operation
> argument to tbe rich comparison API.  My experience with dict
> comparisons was that dict_richcompare couldn't compute Py_LT/LE/GT/GE
> any cheaper than by doing a full cmp, so I put the dict oldcmp back in
> order to avoid having dict richcmp (potentially) compute cmp 3 times
> to fake one cmp.  But if dict richcmp knew a cmp outcome was desired,
> it could compute it with no extra work to speak of.  Then there would
> be no reason at all to hold on to the dict tp_compare slot.
>
> The list and tuple richcmps are also doing almost all the work needed
> to compute a 3-way cmp outcome.

+1 from me; there's one spot in my new Decimal.py where I optimize an
expensive pair of equality tests down to one by using cmp(), and it's
likely that similar cases will pop up.  When I convert to C code, I'll
want to keep doing that.
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