[Python-Dev] Tangent on class level scoping rules (was Re: PEP 463: Exception-catching expressions)

Nick Coghlan ncoghlan at gmail.com
Sat Feb 22 15:42:06 CET 2014

On 22 Feb 2014 09:59, "Greg Ewing" <greg.ewing at canterbury.ac.nz> wrote:
> Nick Coghlan wrote:
>> As Chris later noted, you likely *could* still implement expression
>> local name binding for an except expression without a full closure, it
>> would just be rather difficult.
> I'm still not convinced it would be all *that* difficult.
> Seems to me it would be semantically equivalent to
> renaming the inner variable and adding a finally clause
> to unbind it. Is there something I'm missing?

Dealing with references from nested closures is the hard part. It's not
impossible to solve, but would require introducing a new kind of scope not
previously seen in Python, which is a  rather dubious suggestion when the
existing closure semantics can typically do the job. However, we're getting
off topic for python-dev.


> --
> Greg
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