Question

Problem: Need to parse some specific arguments which could be in any order, non are optional: -h -d -src -dst

Am new to Python and have looked at the alternatives such as getopt and argparse but couldn’t get a working example so went custom as below;

argv=sys.argv[1:]
args=[]
for idx, arg in enumerate(argv):
    # if is arg
    if arg.startswith("-"):
        # find arg match
        for i in ("-h","-d:","-src:","-dst:"):
            # requires var
            if i == arg + ':' and idx < len(argv)-1:
                if not argv[idx+1].startswith("-"):
                    args.append((arg,argv[idx+1]))
                    break
            # no var
            elif i == arg:
                args.append((arg,""))
                break
    else:
        continue
# may contain duplicates
print(args)
# no dupes
print(set(args))

Can anyone suggest improvements and/or better examples to achieve the problem objective?

Answer 1

in python 2.6 there is a module called optparse

which does what you want.

example from the docs:

from optparse import OptionParser
[...]
parser = OptionParser()
parser.add_option("-f", "--file", dest="filename",
                  help="write report to FILE", metavar="FILE")
parser.add_option("-q", "--quiet",
                  action="store_false", dest="verbose", default=True,
                  help="don't print status messages to stdout")

(options, args) = parser.parse_args()

another example:

usage = "usage: %prog [options] arg1 arg2"
parser = OptionParser(usage=usage)
parser.add_option("-v", "--verbose",
                  action="store_true", dest="verbose", default=True,
                  help="make lots of noise [default]")
parser.add_option("-q", "--quiet",
                  action="store_false", dest="verbose",
                  help="be vewwy quiet (I'm hunting wabbits)")
parser.add_option("-f", "--filename",
                  metavar="FILE", help="write output to FILE")
parser.add_option("-m", "--mode",
                  default="intermediate",
                  help="interaction mode: novice, intermediate, "
                       "or expert [default: %default]")