[Python-Dev] Analog of PEP 448 for dicts (unpacking in assignment with dict rhs)

[Ben Usman]

Sounds like that happens quite often.

Yep, I totally agree with your point, I think I mentioned something like
this in the post as a possible partial solution: a drop-in replacement for
an ugly list compression people seem to be using now to solve the problem.
It's easy to implement, but the adoption by community is questionable. I
mean, if this is a relatively rare use case, but those who need it seem to
have their own one-liners for that already, is there even a need for a
method or function like this in standard library? To unify to improve
readability (single standard "getitems" instead of many different get_n,
gets, get_mutliple)? The only motivation I can think of, and even it is
questionable.

On Nov 12, 2017 05:06, "Nick Coghlan" <ncoghlan at gmail.com> wrote:

On 11 November 2017 at 16:22, Jelle Zijlstra <jelle.zijlstra at gmail.com>
wrote:
> 2017-11-10 19:53 GMT-08:00 Ben Usman <bigobangux at gmail.com>:
>> I was not able to find any PEPs that suggest this (search keywords:
>> "PEP 445 dicts", "dictionary unpacking assignment", checked PEP-0),
>> however, let me know if I am wrong.
>>
> It was discussed at great length on Python-ideas about a year ago. There
is
> a thread called "Unpacking a dict" from May 2016.

I tend to post this every time the topic comes up, but: it's highly
unlikely we'll get syntax for this when we don't even have a builtin
to extract multiple items from a mapping in a single operation.

So if folks would like dict unpacking syntax, then a suitable place to
start would be a proposal for a "getitems"  builtin that allowed
operations like:

    b, a  = getitems(d, ("b", "a"))

operator.itemgetter and operator.attrgetter may provide some
inspiration for possible proposals.

Cheers,
Nick.

--
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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