Strange variable scope... is this right?

[gradha at iname.com]

Hi.

In another attempt to DTW (Dominate The World), I wrote an obfuscated loop
just to see the scope behaviour of Python:

f = ["row", "cow", "arrow"]
for f in f:
	print f
	for f in range (len (f)):
		print f

This prints:

row
0
1
2
cow
0
1
2
arrow
0
1
2
3
4

I expected python to bark at me like C would, but from what I read in the
tutorials, this seems to be one of those variable scope issues, right?
AFAICS, python will create a different variable scope at both for's,
hence the possibility to reuse the variable name f, since it means a
different thing at each scope, being unavailable from outside it's scope.

Is this a correct deduction? Is this related with the need to declare in
a function global variables so that if they are modified, the modifications
will be seen outside?

If this is right, I would understand that python duplicates globals (and
local variables if they exist) are duplicated at _each_ new scope. Isn't
this too time consuming? How is this possible?

-- 

 Grzegorz Adam Hankiewicz   gradha at iname.com - http://gradha.infierno.org
 Other web pages:  http://glub.ehu.es/  -  http://welcome.to/gogosoftware/