On Wed, Aug 24, 2016 at 8:54 PM, Shiyao Ma <i...@introo.me> wrote: > Given a = [1, 2] > > a.extend(a) makes a = [1,2, 1,2] > > One might guess a.extend(a) would turn into an infinite loop. It turns out > here Python first gets all the items of `a' and then append them to `a', so > the infinite loop is avoided. >
Be careful: doing the same in Python may not behave that way. >>> a = [1,2] >>> for x in a: a.append(x) ... ^CTraceback (most recent call last): File "<stdin>", line 1, in <module> KeyboardInterrupt >>> len(a) 6370805 That right there, folks, is an infinite loop. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
