Agreed, I've rarely found a need for a "second None" or sentinel either, but
once every few years I do. So, this use case doesn't seem to be common enough
to devote special syntax or a keyword to from my perspective.
But, I'll let you know my secret. I don't make my own sentinel, but rather use
another singleton that is built-in already. And if you squint just right, it
even makes sense.
It is a built-in singleton so rarely known that you will almost never encounter
code with it, so you'll have it all to yourself. Even on a python mailing list,
in a thread about sentinels/singletons, it will not be mentioned. Some may
"consider it unnatural." It is…
…
… (hint)
… (wait for it)
…
>>> Ellipsis
Ellipsis
Don't think I've ever needed a "third None" but if I did I'd probably try an
enum instead.
-Mike
On 2017-03-02 15:02, Barry Warsaw wrote:
On Mar 02, 2017, at 06:37 PM, Brett Cannon wrote:
So to me, there's actually two things being discussed. Do we need another
sentinel to handle the "None is valid" case, and do we want syntax to more
clearly delineate optional arguments?
No, and no (IMHO).
-Barry
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