[Python-ideas] Unpacking a dict

[Eric V. Smith]

On 5/28/2016 1:34 PM, Joao S. O. Bueno wrote:
> On 27 May 2016 at 12:37, Zachary Ware <zachary.ware+pyideas at gmail.com> wrote:
>> On Fri, May 27, 2016 at 10:32 AM, Michael Selik <michael.selik at gmail.com> wrote:
>>>
>>>
>>> On Fri, May 27, 2016 at 11:28 AM Zachary Ware
>>> <zachary.ware+pyideas at gmail.com> wrote:
>>>>
>>>> Here's a crazy thought that might be best dismissed out of hand: what
>>>> about extending 'from name import other_names' to accept any object
>>>> for <name>?  First try to get values via __getitem__() (possibly only
>>>> for dict/dict subclasses?), next try getattr(), finally try to import
>>>> the module and pull values from it as per usual.
>>>>
>>>> Pros:
>>>> - solves dict unpacking
>>>
>>>
>>> Would it solve nested dict unpacking?
>>
>> How do you mean?  Replacing `some_name =
>> some_dict['some_key']['some_name']` with `from some_dict['some_key']
>> import some_name`?
>>
>> Sure, why not? :)
>
> That is the best idea I've seem on this thread.
>
> And them, why having to specify the keys, just to violate DRY?
>
> Maybe just allwoing Mappings to be usedwith  `from ...  import ...`  syntax
> will work nicely, unambiguously, with no new weird syntaxes introduced  -
> and the syntax even allows one to rename the dict keys to other
> variables, with the
> `from mymapping  import a as c,  b  as d "   variant.
>
> That would be certainly nice.

Wouldn't this approach require that the keys be constants? That is, you 
couldn't implement a replacement for:

val = d[key+'bar']

I'm not sure that's a reasonable restriction.

Eric.