[Python-Dev] Scoping vs augmented assignment vs sets (Re: 'fast locals' in Python 2.5)

Josiah Carlson jcarlson at uci.edu
Tue Jun 13 20:49:27 CEST 2006

Boris Borcic <bborcic at gmail.com> wrote:
> NB : That the compiler's interpretation has no use-cases is my crucial point, 
> it's the reason why I dared suggest a design bug - as you seem to take at heart.

I think that Python's compiler with respect to augmented assignment and
nested scopes is proper and sufficient. Believe whatever you want about
my intentions.

> Josiah Carlson wrote:
> > and significantly more readable if it were implemented as a
> > class.
> I'll deny that flatly since first of all the issue isn't limited to closures. It 
> would apply just as well if it involved globals and top-level functions.
> > 
> > class solve:
> >     def __init__(self, problem):
> >         self.freebits = ...
> >     ...
> >     def search(self, data):
> >         ...
> >         self.freebits ^= swaps
> >         ...
> >     ...
> > 
> > Not everything needs to (or should) be a closure
> Right. Let's thus consider
> freebits = ...
> def search(data) :
>      ...
>      freebits ^= swaps

You seem to not realize that these different use-cases.  Your new
example involves a global variable that is *shared* among everyone that
knows  about this particular module.  It also is repaired by a simple
insertion of 'global freebits' at the beginning of the search function. 
The closure/class example is merely a method of encapsulating state,
which I find easier to define, describe, and document than the closure

Back in February, there was a discussion about allowing people to
'easily' access and modify variables defined in lexically nested scopes,
but I believed then, as I believe now, that such attempted uses of
closures are foolish when given classes.  Given the *trivial* conversion
of your closure example to a class, and my previous comments on closures
"I find their use rarely, if ever, truely elegant, [...] more like
kicking a puppy for barking: [...] there are usually better ways of
dealing with the problem (don't kick puppies for barking and don't use
closures).", you are not likely to find me agreeing with you about
augmented assignment and/or lexically nested scopes.

 - Josiah

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