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 -- http://mail.python.org/mailman/listinfo/python-list
