Roy Smith writes: > We've been in the twilight zone for a while. That's when the fun > starts. But, somewhat more seriously, I wonder what, exactly, it is > that freaks people out about: > > >>>> [(new_songs if s.is_new() else old_songs).append(s) for s in songs] > > Clearly, it's not the fact that it build and immediately discards a > list, because that concern is addressed with the generator hack, and > I think everybody (myself included) agrees that's just horrible.
I expect e(s) in [e(s) for s in songs] to be an expression that is evaluated for its value and not for an effect. The comprehension should stand for a list of those values. The one above violates this expectation. > Or, is it the use of the conditional to create the target for append()? > Would people be as horrified if I wrote: > > for s in songs: > (new_songs if s.is_new() else old_songs).append(s) > > or even: > > for s in songs: > the_right_list = new_songs if s.is_new() else old_songs > the_right_list.append(s) These are fine. -- http://mail.python.org/mailman/listinfo/python-list
