[Python-Dev] Add __reversed__ methods for dict

Rémi Lapeyre remi.lapeyre at vint.fr
Thu May 24 08:55:32 EDT 2018


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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