Python Scoping: Run it over me one more time please...

[Justin Sheehy]

"Warren Postma" <embed at geocities.com> writes:

> # But why can't this function modify the global Y:
> Y = 0
> def inc_Y():
>     Y= (Y + 1)
>     return Y

It can, if you add one line.

>>> Y = 0
>>> def inc_Y():
...     global Y
...     Y= (Y + 1) 
...     return Y 
... 
>>> inc_Y()
1
>>> Y
1

Python, in examining your function, saw that you are modifying Y and
decided that it is local.  You just need to tell it that Y is a
global.

This sort of thing is mentioned a couple of times in the FAQ.

http://www.python.org/doc/FAQ.html#4.36
http://www.python.org/doc/FAQ.html#4.57


-Justin