Actually, I would rather like to DO AWAY with the anomalous 'global' statement and its weird anomalies such as:
x = 23
def f1(u): if u: global x x = 45
def f2(): if 0: global x x = 45
print x f2() print x f1(0) print x
"if u:" when u is 0, and "if 0:", should have the same effect to avoid violating the least-astonishment rule -- but when the if's body has a global in it, they don't. Eeek.
Eek. Global statement inside flow control should be deprecated, not abused to show that global is evil. :-)
Plus. EVERY newbie makes the mistake of taking "global" to mean "for ALL modules" rather than "for THIS module",
Only if they've been exposed to languages that have such globals.
uselessly using global in toplevel,
Which the parser should reject.
etc. It's a wart and I'd rather work to remove it than to expand it, even though I _would_ like rebindable outers.
I'd rather have a special name that means "this module" available for import (yes, I can do that with an import hook today). Say that __this_module__ was deemed acceptable for this. Then, import __this_module__ __this_module__.x = 23 lets me rebind the global-to-this-module variable x without 'global' and its various ills. Yeah, the name isn't _too_ cool. But I like the idea, and when I bounced it experimentally in c.l.py a couple weeks ago the reaction was mildly positive and without flames. Making globals a TAD less handy to rebind from within a function would not be exactly bad, either. (Of course 'global' would stay until 3.0 at least, but having an alternative I could explain it as obsolescent:-).
I think it's not unreasonable to want to replace global with attribute assignment of *something*. I don't think that "something" should have to be imported before you can use it; I don't even think it deserves to have leading and trailing double underscores.
Walter suggested 'global.x = 23' which looks reasonable; unfortunately my parser can't do this without removing the existing global statement from the Grammar: after seeing the token 'global' it must be able to make a decision about whether to expand this to a global statement or an assignment without peeking ahead, and that's impossible.
Extending this idea (perhaps overstretching it), some other name "special for import" might indicate outer scopes. Though reserving the whole family of names __outer_<name>__ is probably overdoing it... plus, the object thus 'imported' would not be a module and would raise errors if you tried setattr'ing in it a name that's NOT a local variable of <name> (the import itself would fail if you were not lexically nested inside a function called <name>). Thus this would allow *re-binding* existing local outer names but not *adding* new ones, which feels just fine to me (but maybe not to all).
OK, this is 1/4-baked for the closure issue. BUT -- I'd STILL love to gradually ease 'global' out, think the "import __this_module__" idea is 3/4-baked (lacks a good special name...), and would hate to see 'global' gain a new lease of life for sophisticated uses...;-)
If we removed global from the language, how would you spell assignment to a variable in an outer function scope? Remember, you can *not* use 'outer.x' because that already refers to a function attribute.
--Guido van Rossum (home page: http://www.python.org/%7Eguido/)