[Python-Dev] Explicit Lexical Scoping (pre-PEP?) (original) (raw)

Talin talin at acm.org
Mon Jul 10 01:51:45 CEST 2006

Talin wrote:

Some alternatives:

use x using x with x -- recycle a keyword? reuse x use extant x share x common x same x borrow x existing x Although, to be perfectly honest, the longer this discussion goes on, the more that I find that I'm not buying Guido's argument about it being better to define this at the point of use rather than at the point of definition. I agree with him that "point of use" is more Pythonic, but I'm also beginning to believe that there are some good reasons why many other languages do it the other way. Part of the reason why its so hard to name this feature is that it's real name is something like "Hey, Python, you know that cool funky thing you do with defining variables in the same scope as they are assigned? Well, don't do that here."

(Followup to my own comment)

There are really 3 places where you can indicate that a variable is to be reused instead of redefined: 1) The point of definition in the outer scope, 2) A declaration in the inner scope, and 3) The actual point of assignment.

#1 is what I've been pushing for, #2 is what most of the discussion has been about, #3 has been talked about a little bit in the context of an augmented assignment operator.

I actually like #3 a little better than #2, but not with a new operator. I'm thinking more along the lines of a keyword that modifies and assignment statement:

rebind x = 10

Other possible keywords are: modify, mutate, change, update, change, etc...

My gut feeling is that most code that wants to use this feature only wants to use it in a few places. A good example is fcgi.py (implements WSGI for FastCGI), where they use a mutable array to store a flag indicating whether or not the headers have already been sent.

-- Talin

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