On Fri, Aug 30, 2013 at 5:15 PM, Antoon Pardon <antoon.par...@rece.vub.ac.be> wrote: > Op 30-08-13 06:55, Ben Finney schreef: >> Ben Finney <ben+pyt...@benfinney.id.au> writes: >> >>> Fábio Santos <fabiosantos...@gmail.com> writes: >>> >>>> It is a shame that this is not possible in python. for..if exists in >>>> comprehensions and not in regular loops but that would be nice >>>> sometimes. >>> for foo in (spam for spam in sequence if predicate(spam)): … >> >> Better: >> >> for foo in filter(predicate, sequence): >> process(foo) > > Well better in what way? You now have to translate a predicate > expression into a predicate function. Which AFAIU was one of > the reasons to move away from map/filter to list comprehension. > > As I understand it, python made a move away from map and filter > towards list comprehension. Chris seems to want some of the > possibilities that came with that incorporated into the for > statement. And your suggestion is to go back to the old kind > of filter way.
No, actually Ben's quite right - assuming the predicate is a simple function, of course (Python's lambda notation is a bit clunky for comparisons); as of Python 3, filter() is lazy and is pretty much what I'm doing here. However, that's still a specific answer to a specific (albeit common) instance of wanting to merge control structures. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
