[Python-Dev] Comparison speed (original) (raw)

Aahz Maruch aahz@rahul.net
Sun, 20 May 2001 06:50:08 -0700 (PDT)

Tim Peters wrote:

If the time machine batteries can hold a full charge, you may want to go back and add PyCMP as a seventh possible desired-operation argument to tbe rich comparison API. My experience with dict comparisons was that dictrichcompare couldn't compute PyLT/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 tpcompare 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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