New assignmens ...

[Antoon Pardon]

Op 27/10/2021 om 10:05 schreef Chris Angelico:
> On Wed, Oct 27, 2021 at 6:00 PM Antoon Pardon <antoon.pardon at vub.be> wrote:
>>
>>
>> Op 26/10/2021 om 00:24 schreef Chris Angelico:
>>> TBH, I don't think there's a lot of value in multiple-assignment,
>>> since it has a number of annoying conflicts of syntax and few viable
>>> use-cases. But if you have great examples of "x.y :=" or "x[y] :=",
>>> then by all means, post on python-ideas to propose widening the scope.
>> I think you should seperate the costs from the benefits. It is not because
>> the costs can be high there is little value.
>>
>> And how do you count use cases? What about the following pattern:
>>
>> while (a, b) := next_couple(a,b)[-1]:
>>       ...
>>
>> Is that one use case or is that a use case for each kind of couple?
>>
>> And even if the benefits are little per case, they can add up with every
>> occasion such a case pops up.
>>
> I'm not sure that it's much of a use-case; isn't it an infinite loop as written?

>
> And that's the problem. With multiple-assignment, the overall value is
> going to be the tuple, so you then have to add extra parentheses and
> subscripting to get what you want to check. That makes it far less
> clean, far less tempting, far less valuable. You have to parenthesize
> the assignment target (otherwise it'll build a tuple out of one value
> and the assigned target), then parenthesize again, and subscript at
> the end.
>
> So if you want this added, show a use-case that makes it look way
> better than the alternatives (including a generator, a mid-loop break,
> etc).
>
> ChrisA