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

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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