On 7/8/2018 1:59 PM, Chris Angelico wrote:
On Mon, Jul 9, 2018 at 3:55 AM, Eric V. Smith <[email protected]> wrote:
I agree with Chris in this case. That said, there is at least one place
where the grammar does forbid you from doing something that would otherwise
make be allowable: decorators.
@lookup[0]
File "<stdin>", line 1
@lookup[0]
^
SyntaxError: invalid syntax
But this works:
new_decorator = lookup[0]
@new_decorator
... def f(): pass
Thus, the idea of restricting the type of expression that can be used in
particular circumstances is not without precedent, and should not be
dismissed at face value. That is, unless we want to remove the restriction
on decorators, which I'm okay with, too. I have occasionally wanted to do
something more complicated with a decorator, and used the workaround above.
This is true. I wasn't around when decorator syntax was discussed;
what were the reasons for this being the way it is? It isn't simply
"'@' test".
I was around, but I don't recall the exact reasoning. Something along
the lines of YAGNI, I believe.
The first reference I found to it is
https://mail.python.org/pipermail/python-ideas/2009-September/005623.html,
although surely there are older ones, and even this email references an
older super-confusing use of lambdas in decorators.
In any event, I see no reason to restrict where assignment expressions
can be used.
Eric
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