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

[Abe Dillon]

The problem here is not whether it's explicit. It's about Readability and
conciseness. Using symbols in place of words almost always harms
readability in favor of conciseness.

value = person.name if person.name else person

almost reads like english (aside from being a weird and totally uncommon
use case)

value = person?.name

Is a huge step towards the concise illegible soup of symbols that Perl is
famous for. It's a huge No from me.



On Wed, Jul 25, 2018 at 11:12 AM, Nicholas Chammas <
nicholas.chammas at gmail.com> wrote:

> On Mon, Jul 23, 2018 at 6:05 PM Giampaolo Rodola' <g.rodola at gmail.com>
> wrote:
>
>> This:
>>
>>     v = a?.b
>>
>> ...*implicitly* checks if value is not None [and continues execution].
>> This:
>>
>>     v = a
>>     if a.b is not None:
>>         v = a.b
>>
>> ...*explicitly* checks if value is not None and continues execution.
>>
>
> I think both of those are equally explicit. It's just that one notation is
> more concise than the other. Explicitness and conciseness are related but
> different things.
>
> When something is "explicit", as I understand it, that means it does what
> it says on the cover. There is no unstated behavior. The plain meaning of
> `v = a?.b` is that it expands to the longer form (`v = a; if a.b ...`), and
> it is just as explicit.
>
> This reminds me of something I read about once called Stroustrup's Rule
> <https://thefeedbackloop.xyz/stroustrups-rule-and-layering-over-time/>
>  [1]:
>
> > For new features, people insist on LOUD explicit syntax.
> > For established features, people want terse notation.
>
> I think the "explicit vs. implicit" part of this discussion is probably
> better expressed as a discussion about "loud vs. terse" syntax. None of the
> operators in PEP 505 have implicit behavior, to the best of my
> understanding. It's just that the operators are new and have terse
> spellings.
>
> As a point of comparison, I think a good example of implicit behavior is
> type coercion. When you ask Python to add an int to a float
>
>     a = 3 + 4.5
>
> all that you've explicitly asked for is the addition. However, Python
> implicitly converts the 3 from an int to a float as part of the operation.
> The type conversion isn't anywhere "on the cover" of the + operator. It's
> implicit behavior.
>
> [1] Bjarne Stroustrup makes the observation in this talk
> <https://channel9.msdn.com/Events/Lang-NEXT/Lang-NEXT-2014/Keynote> at
> 23:00.
>
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