Oh, I just found https://mail.python.org/pipermail/python-dev/2017-November/150323.html so I already know what you think: we should go with "dicts preserve insertion order" rather than "dicts preserve insertion order until the first deletion". I guess we should wait for Serhiy to confirm that he's okay with this.
On Thu, Dec 14, 2017 at 6:20 PM, Guido van Rossum <gu...@python.org> wrote: > 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/songofaca >> ndy%40gmail.com >> > >> > > > > -- > --Guido van Rossum (python.org/~guido) > -- --Guido van Rossum (python.org/~guido)
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