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[Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered

Maciej Fijalkowski fijall at gmail.com
Fri Sep 9 05:28:46 EDT 2016 
On Fri, Sep 9, 2016 at 10:55 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Thu, 8 Sep 2016 14:20:53 -0700
> Victor Stinner <victor.stinner at gmail.com> wrote:
>> 2016-09-08 13:36 GMT-07:00 Guido van Rossum <guido at python.org>:
>> > IIUC there's one small thing we might still want to change somewhere
>> > after 3.6b1 but before 3.6rc1: the order is not preserved when you
>> > delete some keys and then add some other keys. Apparently PyPy has
>> > come up with a clever solution for this, and we should probably adopt
>> > it, but it's probably best not to hurry that for 3.6b1.
>>
>> Very good news: I was wrong, Raymond Hettinger confirmed that the
>> Python 3.6 dict *already* preserves the items order in all cases. In
>> short, Python 3.6 dict = Python 3.5 OrderedDict (in fact, OrderedDict
>> has a few more methods).
>
> Is it an official feature of the language or an implementation detail?
>
> Regards
>
> Antoine.

I think an implementation detail (although I'm not opposed to having
it mentioned in the spec), but using the same/similar approach for
sets should be mostly relatively simple, no?

PyPy has a pure python OrderedDict which is a wrapper around dict. For
3.6 it needs an adjustement since new methods showed up
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