[Python-Dev] PEP 468 (Ordered kwargs)

[Maciej Fijalkowski]

Hi Guido.

I *think* part of the reason why our implementation works is that
machines are significantly different than at the times of Knuth.
Avoiding cache misses is a very effective way to improve performance
these days.

Cheers,
fijal

On Sat, Jan 24, 2015 at 7:39 PM, Guido van Rossum <guido at python.org> wrote:
> Wow, very cool. When I implemented the very first Python dict (cribbing from
> an algorithm in Knuth) I had no idea that 25 years later there would still
> be ways to improve upon it! I've got a feeling Knuth probably didn't expect
> this either...
>
> On Sat, Jan 24, 2015 at 2:51 AM, Maciej Fijalkowski <fijall at gmail.com>
> wrote:
>>
>> On Sat, Jan 24, 2015 at 12:50 PM, Maciej Fijalkowski <fijall at gmail.com>
>> wrote:
>> > Hi
>> >
>> > I would like to point out that we implemented rhettingers idea in PyPy
>> > that makes all the dicts ordered by default and we don't have any
>> > adverse performance effects (in fact, there is quite significant
>> > memory saving coming from it). The measurments on CPython could be
>> > different, but in principle OrderedDict can be implemented as
>> > efficiently as normal dict.
>> >
>> > Writeup:
>> > http://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html
>> >
>> > Previous discussion:
>> > https://mail.python.org/pipermail/python-dev/2012-December/123028.html
>> >
>> > Cheers,
>> > fijal
>>
>> also as a sidenote: PEP should maybe mention that PyPy is already
>> supporting it, a bit by chance
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>
>
> --
> --Guido van Rossum (python.org/~guido)