[Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

[Kirill Balunov]

2017-11-29 11:14 GMT+03:00 Nick Coghlan <ncoghlan at gmail.com>:


> It's OK to say "the use case exists, but I still
> don't want that particular syntax for it in Python" (I'm personally
> inclined to agree with you on that front). It's not OK to try to claim
> there are no use cases where the status quo is awkward enough to
> become irritating (since it's an empirically false statement that you
> don't need to be making).
>

If the problem with the proposed syntax, but there are cases for use, it
may be worth to bikeshed one more time?

2017-11-29 9:08 GMT+03:00 Steven D'Aprano <steve at pearwood.info>:

I'd much prefer to read, write and teach the version with ?? over the
> status quo.


Since the proposed semantics is more similar to the idea of "or", may be it
is better to consider something like:

timeout then local_timeout then global_timeout

I do not know how much this is a frequent case to be worthy of a keyword.

With kind regards, -gdg

2017-11-29 11:14 GMT+03:00 Nick Coghlan <ncoghlan at gmail.com>:

> On 29 November 2017 at 16:13, David Mertz <mertz at gnosis.cx> wrote:
> > Strong -1 still from me. Too special case for syntax. Just write a
> function
> > 'first_non_none()' that can perfectly will handle the need.
>
> That's the equivalent of SQL's COALESCE, and it's insufficient for the
> same reason "and" and "or" are syntax rather than builtins: the
> function form doesn't provide short-circuiting behaviour.
>
> As far as utility goes, I put it in a similar category to matrix
> multiplication: if you don't need it, you don't need it, but when you
> do need it, you need it a *lot*.
>
> The use case where these operations come up is when you're working
> with partially structured hierarchical data (*cough*JSON*cough*). In
> those kinds of structures, None is frequently used as a marker to say
> "this entire subtree is missing", and you either want to propagate
> that None, or else replace it with something else (and the "something
> else" may be a network call to a different service, so you definitely
> don't want to do it if you don't need to).
>
> So I'd remind folks to try to avoid the "I don't need this, so nobody
> needs this" mistake. It's OK to say "the use case exists, but I still
> don't want that particular syntax for it in Python" (I'm personally
> inclined to agree with you on that front). It's not OK to try to claim
> there are no use cases where the status quo is awkward enough to
> become irritating (since it's an empirically false statement that you
> don't need to be making).
>
> Cheers,
> Nick.
>
> --
> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
> _______________________________________________
> Python-ideas mailing list
> Python-ideas at python.org
> https://mail.python.org/mailman/listinfo/python-ideas
> Code of Conduct: http://python.org/psf/codeofconduct/
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20171129/b899c76f/attachment-0001.html>