[Python-ideas] PEP 572: Statement-Local Name Bindings

[Chris Angelico]

On Thu, Mar 1, 2018 at 5:03 AM, Kirill Balunov <kirillbalunov at gmail.com> wrote:
>
> The PEP says:
>
>>
>> Omitting the parentheses from this PEP's proposed syntax introduces many
>> syntactic ambiguities.
>
>
> and:
>
>> As the name's scope extends to the full current statement, even a block
>> statement, this can be used to good effect in the header of an if or while
>> statement
>
>
>
> Will the `from ... import ... as ... statement be a special case, because
> currently the following form is valid:
>
> from math import (tau as two_pi)

No, because that statement doesn't have any expressions in it - it's a
series of names. The "tau" in that line is not looked up in the
current scope; you can't write a function that returns the symbol
"tau" and then use that in the import. So the grammatical hook that
enables "(... as ...)" doesn't apply here.

ChrisA