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

[Mario Corchero]

Do you mean making getitems call itemgetter?

At the moment we can already do with itemgetter:

  from operator import itemgetter
  a,b = itemgetter("a", "b")(d)


> 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.

You mean subitems as attrgetter does? That would be actually quite cool!

  d = dict(a=dict(b=1), b=dict(c=2))
  ab, ac = itemgetter("a.b", "b.c", separator=".")(d)


I've created an issue in case something like that is desired:
https://bugs.python.org/issue32010
No real strong push for it, happy to just close it if it does not get
interest.

That said I am not sure it solves Ben requests as he seamed to be
targetting a way to bind the variable name with the dictionary keys
implicitly.

On 12 November 2017 at 10:06, 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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