[Python-Dev] Guarantee ordered dict literals in v3.7? (original) (raw)

Paul Moore p.f.moore at gmail.com
Tue Dec 19 06:04:34 EST 2017

On 19 December 2017 at 08:27, Nathaniel Smith <njs at pobox.com> wrote:

On Mon, Dec 18, 2017 at 11:38 PM, Steve Dower <steve.dower at python.org> wrote:

On 18Dec2017 2309, Steven D'Aprano wrote:

[A LOT OF THINGS I AGREE WITH] I agree completely with Steven's reasoning here, and it bothers me that what is an irrelevant change to many users (dict becoming ordered) seems to imply that all users of dict have to be updated. Can we all take a deep breath and lay off the hyperbole? The only point under discussion in this subthread is whether pprint -- our module for producing nicely-formatted-reprs -- should continue to sort keys, or should continue to provide an accurate repr. There are reasonable arguments for both positions, but no-one's suggesting anything in the same solar system as "all users of dict have to be updated". Am I missing some underlying nerve that this is hitting for some reason?

IMO, the key thing is that people appear to be talking as if changing documented behaviour without deprecation is acceptable. Or even if they are OK with a deprecation period, they are still talking about changing documented behaviour for a trivial reason (as Steve Dower said, most people will still use dict for its dict behaviour, not for its orderedness). People (including me) are getting irritated because backward compatibility, which is normally a key principle, is being treated so lightly here. (It happened in another thread as well - changing the output of csv.DictReader from OrderedDict to dict - again suggesting that breaking a documented behaviour was OK, just because dicts are now ordered).

Paul

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