[Python-ideas] PEP 505: None-aware operators

[Giampaolo Rodola']

On Mon, Jul 23, 2018 at 3:12 AM Steven D'Aprano <steve at pearwood.info> wrote:
> > ? has no spaces, it's literally "variable names interrupted by
> > question marks" and evaluation can stop at any time while scanning the
> > line from left to right.
>
> Just like ordinary attribute access.
>
> This is the point I was making earlier: you accept existing punctuation
> doing these things:
>
>     try:
>         obj.spam.egsg.tomato.cheese  # oops a typo
>     except AttributeError:
>         # evaluation can stop at any time
>         ...
>
> while demanding a higher standard for new punctuation.
>
> All of your criticisms of ? punctuation applies to . as well.

I don't think they do. For once, "a.b" does one and one thing only,
"a?.b" does two and that's a fundamental difference (explicitness). It
does so by introducing a brand new operator ("?") which can be spelled
in two forms ("a?.b" and "a?[b]") by using two adjacent symbols not
interrupted by any space, which is an absolute first in the Python
syntax and that's the second and fundamental difference. I cannot move
the same criticism to the "a.b" form: it's simpler, it does one thing
and it uses one symbol.

Your argument is basically a revisitation of "it's just another
symbol" and "it's like a + b" which you have being pulling different
times in this thread already. You want to imply that since symbols are
already used in the grammar (and "." in particular) then it's
perfectly fine to also have "?" and its spell variants (which are 4 in
total). I don't think that's how changes of such importance should be
discussed.

> > Multiple "?" can live on the same line so
> > that's incentive to write one-liners, really, and to me one-liners are
> > always less explicit than the same logic split on multiple lines.
>
> Explicit is not always better.
>
>     import this
>
> is much better than:
>
>     for location in sys.path:
>         try:
>             for file in os.listdir(location):
>                 if os.splitext(file) in ('.pyc', '.py', '.so'):
>                     ...

I honestly don't see how this example is related with anything discussed so far.

> If punctuation is unreadable and Perlish, so is "." and ":" punctuation.
> If ?? is bad because it is "implicit", then so is import or sorted.

I'm not even sure how to reply to this.

-- 
Giampaolo - http://grodola.blogspot.com