[Python-Dev] Using and binding relative names (was Re: PEP for Better Control of Nested Lexical Scopes)

Steven Bethard steven.bethard at gmail.com
Thu Feb 23 17:19:08 CET 2006

On 2/22/06, Almann T. Goo <almann.goo at gmail.com> wrote:
> Since the current semantics allow *evaluation* to an enclosing scope's
> name by an "un-punctuated" name, "var" is a synonym to ".var" (if
> "var" is bound in the immediately enclosing scope).  However for
> *re-binding* to an enclosing scope's name, the "punctuated" name is
> the only one we can use, so the semantic becomes more cluttered.
> This can make a problem that I would say is akin to the "dangling else problem."
>     def incrementer_getter(val):
>        def incrementer():
>            val = 5
>            def inc():
>                ..val += 1
>                return val
>            return inc
>        return incrementer
> Building on an example that Steve wrote to demonstrate the syntax
> proposed, you can see that if a user inadvertently uses the enclosing
> scope for the return instead of what would presumably be the outer
> most bound parameter.  Now remove the binding in the incrementer
> function and it works the way the user probably thought.

Sorry, what way did the user think?  I'm not sure what you think was
supposed to happen.

Grammar am for people who can't think for myself.
        --- Bucky Katt, Get Fuzzy

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