On Thu, 2006-11-30 at 16:26 -0800, John Machin wrote: > Fredrik Tolf wrote: [...] > > The thing is, I want to get format strings from the user, and I don't > > want to require the user to consume all the arguments. docs.python.org > > doesn't seem to have any clues on how to achieve this, and I can't think > > of what to google for. > > Three approaches spring to mind. In descending order of my preference: > > (a) don't do that
It would be a possibility, since all current uses actually do have the right number of parameters. I would just like to keep the option available. > (b) parse the format string, counting the number of args required. If > the user has supplied more, throw them away. I was thinking of that, but it just seems far too ugly. > (c) wrap your execution of format_string % args in a try/except > bracket. If you get a TypeError with that message [not guaranteed to > remain constant in the future], throw away the last arg and go around > again. That might be a good possibility. Thanks for the idea! I do consider it quite a bit ugly, but that often happens when languages try to police programmers... :P > As a matter of curiosity, why don't you want the user to consume all > the arguments? Don't they get even a teensy-weensy warning message? Are > you writing a Perl interpreter in Python? Well basically, I'm rewriting a autodownloader for a file-sharing network in Python (previously written as a bash script, using the printf command), and I have a number of files scattered over my hard drive specifying search expressions, into which a potentially optional episode number can be inserted using sprintf-like arguments (using fsexpr="`printf "$sexpr" "$curep"`" in bash). I would like to keep it as a printf parameter, in order to be able to write e.g. %02i, and I would like to keep it optional, for downloading non-episoded stuff. I couldn't help noticing that the named variant of the % operator (using a dict, that is) doesn't require all its arguments to be consumed. Using that would require me to rewrite *all* the existing files, though. Anyway, thanks! Fredrik Tolf -- http://mail.python.org/mailman/listinfo/python-list
