Guido van Rossum wrote:
> On Wed, Jul 1, 2020 at 5:50 PM Nick Coghlan [email protected] wrote:
> > The key thing I'm hoping for in PEP 622 itself is
> > that "Syntactic compatibility with a possible future
> > enhancement to assignment statements" be considered
> > as a constraint on the syntax for case patterns.
> That would certainly rule out ideas like writing stores as $x or x? or <x>
> etc., since it would be syntactically incompatible with current
> assignment statements.
No; it would be unfortunate that it creates a second way to
do things, but it wouldn't rule them out. The problem Nick
pointed out is for syntax that is already meaningful, but
means something different.
self.y = 15
already has a meaning, but that meaning is NOT "don't really
assign to X, I am using it as a constant defined elsewhere."
?x = 14
?self.y = 15
do not yet mean anything, and if they end up being a more
explicit (but also more verbose) variant of
x = 14
self.y = 15
that is probably sub-optimal, but it isn't any worse than :=
The slight variation triggered by the "?" of ?var would be
shorthand for "and if you can't make the entire assignment
work, pretend I never even asked", so that
?x, 0 = (4,5)
would not lose or shadow a previous binding of x.
-jJ
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