OptParser has defeated me. Assistance required.

[Stev0]

Working on a small program in python 3.1, using the OptParse module, however its throwing the error message every time. I figure I have something wrong in the error related if statement, but I cant find it. Any of you more experienced optparse users see the problem?

#! /usr/bin/python3.1

import sys

from optparse import OptionParser

def main():

usage = "usage: %prog [options] [target]"
parser = OptionParser()
parser.set_usage(usage)
parser.add_option("-a", "--address", action="store", dest="addy", help="blah")
parser.add_option("-r", "--range", action="store", dest="range", help="blah")
(options, args) = parser.parse_args()

if len(args) !=1:
parser.error("Please use an option to specify the target.")
addy = options.addy
do_something_with_addy(addy)now when I run the script with ./<script> -a www.test.com (http://www.test.com), it throws the error message every time. Where have I made the mistake?

[snova]

Working on a small program in python 3.1, using the OptParse module, however its throwing the error message every time. I figure I have something wrong in the error related if statement, but I cant find it. Any of you more experienced optparse users see the problem?

#! /usr/bin/python3.1

import sys

from optparse import OptionParser

def main():

usage = "usage: %prog [options] [target]"
parser = OptionParser()
parser.set_usage(usage)
parser.add_option("-a", "--address", action="store", dest="addy", help="blah")
parser.add_option("-r", "--range", action="store", dest="range", help="blah")
(options, args) = parser.parse_args()

if len(args) !=1:
parser.error("Please use an option to specify the target.")
addy = options.addy
do_something_with_addy(addy)now when I run the script with ./<script> -a www.test.com (http://www.test.com), it throws the error message every time. Where have I made the mistake?

If you run it like that, the "www.test.com" argument will become options.addy, as you expect. But it will not be found in args in any case; args is the list of leftovers. Now, if you had run it like this (without -a):


./<script> www.test.com

Then args would have contained this, but options.addy would have been unspecified.

It is not possible to specify -a without also passing an argument. If -a is required somehow then you need to test for this some other way. For example:



if options.addy is None:
parser.error("You must specify an address.")

[Stev0]

Ok that helped. But I've run into another problem :) The other command line option :) How would I incorporate that into the error message so I can use options.range later?

Edit: Nevermind, I just figured out the wonder that is if len(args) is None:

[snova]

Edit: Nevermind, I just figured out the wonder that is if len(args) is None:

Wouldn't that always be False? len() either returns an integer or throws an exception; it's not possible for it to return None.

If you've solved your problems, great, but you've left me a little confused.