[Ed Kellett <e+python-id...@kellett.im>]
> How about if you just can't have an expression in a local()?
See the quadratic equation example in the original post. When working
with expressions, the entire point of the construct is to define
(sub)local names for use in a result expression.
> There are a few obvious alternative possibilities:
>
> 1. No special case at all:
>
> local(x=1, y=2, _=x+y)
As above.
> 2. Co-opt a keyword after local():
>
> local(x=1, y=2) in x+y
Requiring "in" requires annoying syntactic repetition in the common
if local(match=re.match(regexp, line)) in match:
kinds of cases. Making "in" optional instead was discussed near the
end of the original post. I agree that your spelling just above is
more obvious than `local(x=1, y=2, x+y)` which is why the original
post discussed making an "in clause" optional. But, overwhelmingly,
it appears that people are more interested in establishing sublocal
scopes in `if` and `while` constructs than in standalone expressions,
so I picked a spelling that's _most_ convenient for the latter's
common "just name a result and test its truthiness" uses.
> 3. Co-opt a keyword inside local():
>
> local(x=1, y=2, return x+y)
Why would that be better than local(x=1, y=2, x+y)? That no binding
is intended for `x+y` is already obvious in the latter.
> I hate the first and wish the _ pattern would die in all its forms, but
> it's worth mentioning. I don't think there's much to choose between the
> other two, but 2 uses syntax that might have been valid and meant
> something else, so 3 is probably less confusing.
Indeed, 3 is the only one I'd consider, but I don't see that it's a
real improvement. It seems to require extra typing every time just to
avoid learning "and it returns the value of the last expression" once.
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