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

Brett Cannon brett at python.org
Fri Sep 9 12:52:21 EDT 2016

On Fri, 9 Sep 2016 at 01:58 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?

It depends on the context. **kwargs is now defined to be an ordered mapping and PEP 520 has been updated to drop definition_order and to say that cls.dict is an ordered mapping. Otherwise we have not made dict itself ordered everywhere.

And there has been discussion to rip out the C code for OrderedDict and change the Python code to subclass dict so it only has to provide its additions to the dict API. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20160909/ee191430/attachment.html>

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