On Tue, Oct 20, 2020 at 11:26 AM Steven D'Aprano <st...@pearwood.info>
wrote:
> I can't say that I like the look of pseudo-assignment to question mark:
>
> for ? in range(20):
> ...
>
> but I could probably learn to live with it. But one of your
> rationalisations:
>
>
> > and makes it more obvious that
> > the actual intent is for the value to be unused -- since it is entirely
> > impossible to use it.
>
> is actually an anti-feature, in my opinion.
>
> I think that people might like the idea of not actually binding a value
> in situations like this:
>
> a, *?, b = expression
>
> until you end up with something unexpected in a and b and need to debug
> what it going on, either in a debugger or with print:
>
> a, *?, b = expression
> print(?) # wait this doesn't work;
>
I'm not sure how this is different than, say,
a, _, _ = range(3)
print(_)
or
a = range(3)[0]
print(<whatever the second value is>)
That is to say, some things are impossible; if you want to print the value,
don't assign to '?'.
>
> In my opinion, having a convention to treat certain variables as
> "unused" is great (I'm partial to `__` myself, to avoid clobbering the
> special variable `_` in the REPL). But having that be a pseudo-variable
> which is *actually* unused and unuseable strikes me as being an
> attractive nuisance.
>
And yet that's exactly what is being proposed in pattern matching.
https://www.python.org/dev/peps/pep-0634/#id3
>
> --
> Steve
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