Is there any good reason to ever use globals anywhere other than as the first statement (after doc string) of a function?
If the use of the global is fairly localized, I sometimes like to have the global declaration immediately proceed the first use, assuming all other uses are in the same indented block. (This means that I sometimes *do* have global inside flow control, but then all uses are also inside the same branch.) But I'm not sure this is a *good* reason.
If not, could its usage be so restricted (like __future__ import)?
This would break way too much stuff. It would have been a good idea for 0.1. But then I was trying to keep the grammar small while keeping syntactic checks out of the compilation phase if at all possible, and I thought "screw it -- if import can go anywhere, so can global."
Plus. EVERY newbie makes the mistake of taking "global" to mean "for ALL modules" rather than "for THIS module",
Part of my brain still thinks that, and another part has to say, 'no, just modular or mod_vars()'.
Only if they've been exposed to languages that have such globals.
Like Python with __builtins__? which I think of as the true globals.
Hardly, since they aren't normally thought of as variables.
Do C or Fortran count as such a source of 'infection'?
C, definitely -- it has the concept and the terminology. In Fortran, it's called common blocks (similar in idea to ABC's SHARE).
uselessly using global in toplevel,
Which the parser should reject.
Good. The current nonrejection sometimes leads beginners astray because they think it must be doing something.
Just like x + 1 I suppose. I'm sure PyChecker catches this.
While I use global/s() just fine, I still don't like the names. I decided awhile ago that they must predate import, when the current module scoop would have been 'global'.
No, they were both there from day one. Frankly, I don't think in this case newbie confusion is enough of a reason to switch from global to some other keyword of mechanism. Yes, this means I'm retracting my support for Alex's "replace-global-with-attribute-assignment" proposal -- Jeremy's objection made me realize why I don't like it much. --Guido van Rossum (home page: http://www.python.org/~guido/)