[Python-ideas] Dict(x, y) -> Dict(zip(x, y))

[Andrew Barnert]

On Feb 14, 2016, at 18:43, Bruce Leban <bruce at leban.us> wrote:
> 
> this would have:
> 
> >>> dict(((1,2),(3,4)))
> {1: 2, 3: 4}
> 
> >>> dict(((1,2),(3,4)), ((5,6)))
> {(1, 2): 5, (3, 4): 6}
> 
> in other words, the interpretation of the first argument to dict is entirely different if there is a second argument than if there isn't one.

It would be nice if we could make Oscar's new parameters keyword-only:

    dict(keys=spam, values=eggs)

Then it's _not_ the first argument that's being interpreted differently.

Unfortunately, we can't do this, because it would be ambiguous with the dict(a=1, b=2) constructor. 

But what about a classmethod named constructor (with or without keyword-only params, depending on how long the name is):

    dict.kv(keys=spam, values=eggs)
    dict.from_keys_values(spam, eggs)

That's pretty close to the idiomatic way to build dictionaries in ObjectiveC:

    [NSDict dictionaryWithValues:eggs forKeys:spam]

... so it's not totally unprecedented.

Still, it raises the obvious question of whether "dict.kv" is much better than "dictkv", which anyone can write for himself as a one-liner if he wants it...
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