[Python-Dev] Add __reversed__ methods for dict

[Antoine Pitrou]

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
> _______________________________________________
> Python-Dev mailing list
> Python-Dev at python.org
> https://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe: https://mail.python.org/mailman/options/python-dev/python-python-dev%40m.gmane.org