[Python-ideas] PEP 505 (None coalescing operators) thoughts

[MRAB]

On 2015-09-29 21:43, Jeff Hardy wrote:
> On Tue, Sep 29, 2015 at 10:35 AM, Barry Warsaw <barry at python.org
> <mailto:barry at python.org>> wrote:
>
>     On Sep 28, 2015, at 03:04 PM, Carl Meyer wrote:
>
>     >But even if they are rejected, I think a simple `??` or `or?` (or
>     >however it's spelled) operator to reduce the repetition of "x if x is
>     >not None else y" is worth consideration on its own merits. This operator
>     >is entirely unambiguous, and I think would be useful and frequently
>     >used, whether or not ?. and ?[ are added along with it.
>
>     But why is it an improvement?  The ternary operator is entirely
>     obvious and
>     readable, and at least in my experience, is rare enough that the
>     repetition
>     doesn't hurt my fingers that much.  It seems like such a radical,
>     ugly new
>     syntax unjustified by the frequency of use and readability improvement.
>
>
> I use it all over the place in C# code, where it makes null checks much
> cleaner, and the punctuation choice makes sense:
>
>      var x = foo != null ? foo : "";
>      var y = foo ?? "";
>
>   (it also has other uses in C# relating to nullable types that aren't
> relevant in Python.)
>
> I'd argue the same is true in Python, if a decent way to spell it can be
> found:
>
>      x = foo if foo is not None else ""
>      y = foo or? ""
>
> It's pure syntactic sugar, but it *is* pretty sweet.
>
> (It would also make get-with-default unnecessary, but since it already
> exists that's not a useful argument.)
>
It's only just occurred to me that there's a small inconsistency here.
The "?.", "?[" and "?(" will short-circuit on None, whereas the "??"
will short-circuit on non-None.

Would that cause any confusion in practice?