On 24/07/2012 02:19, Andrew Cooper wrote:
On 23/07/2012 15:50, Stone Li wrote:
I'm totally confused by this code:
Code:
a = None
b = None
c = None
d = None
x = [[a,b],
[c,d]]
e,f = x[1]
print e,f
c = 1
d = 2
print e,f
e = 1
f = 2
print c,d
Output:
None None
None None
1 2
I'm expecting the code as:
None None
1 2
1 2
What's wrong?
And this question made my GUI program totally out of control.
Thanks
c = 1 and d = 2 are overwriting the variable c (= None) and d (= None)
with new variables 1 and 2. As x already captured c and d while they
were none, the variables e and f do not change (not would the, even if
you subsequently changed x)
Python is a statically scoped language, whereas the functionality you
are expecting would be an example of dynamically scoped.
Care to reveal your programming background?
~Andrew
<duck and cover>
strictly speaking Python doesn't have variables, it has names. This
will possibly start a flame war which, by the standards of this ng/ml,
will be an intense conflagration, hence the duck and cover.
</duck and cover>
--
Cheers.
Mark Lawrence.
--
http://mail.python.org/mailman/listinfo/python-list
