On Sun, 6 Mar 2022 at 21:41, Christopher Barker <python...@gmail.com> wrote:
>
>
>> Personally, I'm certainly not ignoring comprehensions. "for thing in
>> (x for x in collection if is_interesting(x))" uses comprehensions just
>> fine, if you don't like the verbosity of "x for x in", then that's an
>> issue with comprehensions, not a reason why comprehensions don't
>> address this issue, surely? (Personally, I find the repetitiveness of
>> "x for x in" mildly annoying, but not enough to put me off
>> comprehensions[1]).
>
>
> Earlier on the thread, I made a similar point that it would be nice to have a
> way to filter without the redundant for x in x. Though I can’t think of a
> really good way to express it. But as for filtered for loops:
>
> "for thing in
> (x for x in collection if is_interesting(x))"
>
> It not so much the extraneous “x for x” as the duplicated “for thing in” that
> bugs me.
>
> I’m curious— to the skeptics: do you think that The above (or a later if
> block) is just as good or better than
>
> for thing in collection if isinteresting(thing):
>
> Or just that it’s not worth it to make a change.
I think that
for thing in collection:
if not isinteresting(thing): break
...
is at least as good as
for thing in collection if isinteresting(thing):
...
and better in many ways (most importantly for me, it works in older
versions of Python, which is important for libraries that support
multiple versions).
I think that
for thing in (x for x in collection if isinteresting(x)):
...
is only marginally worse, and not sufficiently worse to justify new syntax.
> But the other part of why I think comprehensions are relevant is that
> introducing anf if to the for statement is not brand new syntax - it would be
> allowing existing syntax in a new context that is highly related.
Agreed, this makes the impact of new syntax smaller. But I'm not
really worried about that. It's not that it's a big change, just that
it *is* a change, and there's a minimal cost for *any* change to the
language definition. So someone has to care enough to pay that cost
(in terms of writing a PEP, an implementation, and documentation, and
in terms of going through the process of getting the change accepted).
> And as for documentation and all that, it’s hard to imagine very many people
> not understanding what it means.
>
> Do I care enough to write a PEP? No. So this, like many other small ideas,
> will probably die on the vine.
Yes, this is the real problem. It's simply not compelling enough, even
for supporters of the idea, for them to do the necessary work to make
it happen.
> Oh well.
Indeed.
Paul
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