Senthil Kumaran <sent...@uthcode.com> writes: > On Wed, Jan 11, 2012 at 09:49:58AM +0530, Noufal Ibrahim wrote: > >> > It is not clear what you want from your description. To check if a >> > list is empty, see if len( list ) is zero. >> >> You don't want to do that. Your "list" might be a generator (unless you >> check for type which is a bad idea anyway) and "len"ing that will >> consume it which might be a potentially expensive operation. > > While the explaination on __nonzero__ is useful out of this context, > how can list be a generator? I am assuming that none are confusing the > terminologies.
A list can't be a generator but if you write a function to receive an iterable x and then do a len(x) to check it it's True or False, it will work fine for lists but passing a generator this function might have unpredictable results. That's why I'm cautioning against using `len` to check for whether an object is empty or not. > In practical cases for testing boolean in lists, just use the list as > the test. Empty list is false. Agreed. This is the right way to do it rather than using len. -- ~noufal http://nibrahim.net.in Why don't you pair `em up in threes? -Yogi Berra _______________________________________________ BangPypers mailing list BangPypers@python.org http://mail.python.org/mailman/listinfo/bangpypers
