On Thu, 06 Dec 2012 13:51:29 +0000, Neil Cerutti wrote: > On 2012-12-06, Steven D'Aprano > <steve+comp.lang.pyt...@pearwood.info> wrote: >> total = 0 >> for s in list_of_strings: >> try: >> total += int(s) >> except ValueError: >> pass # Not a number, ignore it. > > If it's internal data, perhaps. Of course, that would mean I had the > option of *not* creating that stupid list_of_strings.
Not necessarily, it depends on the application. If you have a spreadsheet, and create a formula =SUM(A1:A50) the expected behaviour is to just skip anything that is not a valid number, not raise an error. Sometimes correct application-level behaviour is to just ignore input that it doesn't care about. One of the things that I used to despise with a passion about MYOB is that if you clicked on the window outside of a button or field, it would scream at you "ERROR ERROR ERROR - that was not a button or field!!!!" That is to say, it would beep. I mean, *who fscking cares* that the user clicks in the window background? It's a harmless tick, like tapping your desk, just ignore it. As a general rule, library functions should be strict about reporting errors, while applications may be more forgiving about errors that they don't care about. The "don't care about" part is important though -- your word processor shouldn't care about low level networking errors, but it should care if it can't save a file to a network drive. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
