I'm in favor of stating that dict keeps order as part of the language spec.
However re-reading https://mail.python.org/pipermail/python-dev/2017-November/150381.html there's still a point of debate: should it be allowed if dict reorders after deletion (presumably as a result of a rehash)? I'm in favor of prescribing that the order should be preserved even in that case, but I realize there's additional implementation work to be done. Inada-san, what do you think of this? --Guido On Thu, Dec 14, 2017 at 6:03 PM, INADA Naoki <songofaca...@gmail.com> wrote: > Hi, folks. > > TLDR, was the final decision made already? > > If "dict keeps insertion order" is not language spec and we > continue to recommend people to use OrderedDict to keep > order, I want to optimize OrderedDict for creation/iteration > and memory usage. (See https://bugs.python.org/issue31265#msg301942 ) > > If dict ordering is language spec, I'll stop the effort and > use remaining time to another optimizations. > > My thought is, +1 to make it language spec. > > * PHP (PHP 7.2 interpreter is faster than Python) keeps insertion order. > So even we make it language spec, I think we have enough room > to optimize. > > * It can make stop discussion like "Does X keeps insertion order? > It's language spec?", "What about Y? Z?". Everything on top of dict > keeps insertion order. It's simple to learn and explain. > > Regards, > INADA Naoki <songofaca...@gmail.com> > > > On Sun, Nov 5, 2017 at 3:35 AM, Guido van Rossum <gu...@python.org> wrote: > > This sounds reasonable -- I think when we introduced this in 3.6 we were > > worried that other implementations (e.g. Jython) would have a problem > with > > this, but AFAIK they've reported back that they can do this just fine. So > > let's just document this as a language guarantee. > > > > On Sat, Nov 4, 2017 at 10:30 AM, Stefan Krah <ste...@bytereef.org> > wrote: > >> > >> > >> Hello, > >> > >> would it be possible to guarantee that dict literals are ordered in > v3.7? > >> > >> > >> The issue is well-known and the workarounds are tedious, example: > >> > >> > >> https://mail.python.org/pipermail/python-ideas/2015- > December/037423.html > >> > >> > >> If the feature is guaranteed now, people can rely on it around v3.9. > >> > >> > >> > >> Stefan Krah > >> > >> > >> > >> _______________________________________________ > >> Python-Dev mailing list > >> Python-Dev@python.org > >> https://mail.python.org/mailman/listinfo/python-dev > >> Unsubscribe: > >> https://mail.python.org/mailman/options/python-dev/guido%40python.org > > > > > > > > > > -- > > --Guido van Rossum (python.org/~guido) > > > > _______________________________________________ > > Python-Dev mailing list > > Python-Dev@python.org > > https://mail.python.org/mailman/listinfo/python-dev > > Unsubscribe: > > https://mail.python.org/mailman/options/python-dev/ > songofacandy%40gmail.com > > > -- --Guido van Rossum (python.org/~guido)
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