"Martin v. Löwis" martin at v.loewis.de
Sun Mar 13 00:41:23 CET 2011

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Am 12.03.11 18:00, schrieb Glenn Linderman:
>   On 3/12/2011 1:55 PM, Fredrik Johansson wrote:
>> Consider sorting a list of pairs representing fractions. This can be
>> done easily in Python 2.x with the comparison function lambda
>> (p,q),(r,s): cmp(p*s, q*r). In Python 2.6, this is about 40 times
>> faster than using fractions.Fraction as a key function.
>
> Am I correct in concluding that various ideas to eliminate or limit the
> size of the key= cache would not help this use case at all?

That's correct. However, there is a straight-forward day of getting
the same comparison algorithm with the cmp_to_key class in 3.x.
Fredrik classified this as "ugly and slow"; I'm not sure where this
classification comes from.

Regards,
Martin

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