On Apr 2, 6:33 pm, "Rhodri James" <rho...@wildebst.demon.co.uk> wrote: > On Fri, 03 Apr 2009 02:07:38 +0100, grocery_stocker <cdal...@gmail.com> > wrote: > > > Okay, I was thinking more about this. I think this is also what is > > irking me. Say I have the following.. > > >>>> a = [1,2,3,4] > >>>> for x in a: > > ... print x > > ... > > 1 > > 2 > > 3 > > 4 > > > Would 'a' somehow call __iter__ and next()? If so, does python just > > perform this magically? > > No. It's "for" that invokes the iteration protocol; that's pretty > much the definition of it. You have read the iteration protocol > after it's been mentioned so many times now, haven't you? > > "for" calls iter(a), which in turn calls a.__iter__(), to get an > iterator. Once it's got, "for" calls next() on the iterator each > time round the loop. Very approximately, that little for-loop > translates to: > > a = [1,2,3,4] > i = iter(a) > try: > while True: > x = i.next() > print x > except StopIteration: > pass >
Okay, at the risk of sounding like a total slacker, I've only briefly scanned over the iteration protocol. After I get up in the morning, I'll probably read it more closely. -- http://mail.python.org/mailman/listinfo/python-list
