On 11/09/06, Hari Sekhon <[EMAIL PROTECTED]> wrote: > Tim Williams wrote: > > On 11/09/06, Hari Sekhon <[EMAIL PROTECTED]> wrote: > >> > >> Steve Holden wrote: > >> Hari Sekhon wrote: > >> > >> > >> The easiest way to test whether the command will run is to try and run > >> it. If the program doesn't exist then you'll get an exception, which you > >> can catch. Otherwise you'll be stuck with non-portable mechanisms for > >> each platform anyway ... > >> > >> regards > >> Steve > >> > >> > >> Yeah, this occurred to me just after I sent the mail, but I don't > >> really > >> want to run the program because it will go off and do some work and take > >> time to come back. If there is a better way then that would be great. I > >> can't think of anything other than what you have suggested with a > >> message > >> saying that the program wasn't found in the path which would be the most > >> appropriate error since the path could also be wrong. > > > > > > If you run your wrapper and the program exists then you don't have to > > test for it, so the overall process is quicker and cleaner than > > testing-for *then* running the program > > > > If you run your wrapper and the program doesn't exist, then you have > > performed your "if exists" test without extra code and with very > > little processing, and the raised exception will lead you nicely into > > your "not exists" scenario. > > > > try: > > run_somecommand > > except: > > print "you don't have %s installed" % somecommand > > > > > > HTH :) > > > The down side to that is the program has to be run which consumes time > and slows the script down a fair bit (as well as outputting garbage to > the screen) >
Sorry, I don't follow!! If the program doesn't exist how can you run it ??? If the program does exist then running is what you wanted it to do anyway and you've saved doing a test for it first. :) -- Tim Williams -- http://mail.python.org/mailman/listinfo/python-list
