[Python-Dev] Add reversed methods for dict (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Fri May 25 12:32:01 EDT 2018

It's worth nothing that OrderedDict already supports reversed(). The argument could go both ways:

  1. dict is similar to OrderedDict nowadays, so it should support reversed() too;

  2. you can use OrderedDict to signal explicitly that you care about ordering; no need to add anything to dict.

Regards

Antoine.

On Thu, 24 May 2018 14:55:32 +0200 Rémi Lapeyre <remi.lapeyre at vint.fr> wrote:

Hi, since dict keys are sorted by their insertion order since Python 3.6 and that it’s part of Python specs since 3.7 a proposal has been made in bpo-33462 to  add the reversed method to dict and dict views. Concerns have been raised in the comments that this feature may add too much  bloat in the core interpreter and be harmful for other Python implementations. Given the different issues this change creates, I see three possibilities: 1. Accept the proposal has it is for dict and dict views, this would add about 300 lines and three new types in dictobject.c 2. Accept the proposal only for dict, this would add about 80 lines and one new type in dictobject.c while still being useful for some use cases 3. Drop the proposal as the whole, while having some use, reversed(dict(a=1, b=2)) may not be very common and could be done using OrderedDict instead. What’s your stance on the issue ? Best regards, Rémi Lapeyre

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