Python doesn't follow it's own scoping rules?

[Fredrik Lundh]

Tim Danner <tdanner at drpepper.baker.rice.edu> wrote:
> Consider this python program:
> 
> a = 0
> 
> def death_and_destruction():
>     a = a + 1
> 
> death_and_destruction()
> print a
> 
> My understanding is that it should print "1".

that's only because you haven't read the
FAQ or the language reference. read on.

> Unfortunately, it prints:
> 
> Traceback (innermost last):
>   File "evil.py", line 6, in ?
>     death_and_destruction()
>   File "evil.py", line 4, in death_and_destruction
>     a = a + 1
> NameError: a
> 
> This is very strange, and in general Not Good.

checking the FAQ before positing is Good,
though:

http://www.python.org/doc/FAQ.html#4.57

(summary: if Python has determined that a name
is local, it doesn't look it up in the global name-
space).

in addition to the FAQ, I suggest reading the
language reference, especially the section
titled "code blocks, execution frames, and
namespaces".

</F>