python - sys.argv and flag identification

Question

when I accept arguments how do I check if two show up at the same time without having a compound conditional

i.e.

#!/usr/bin/python
import random, string
import mymodule
import sys

z = ' '.join(sys.argv[2:])
q = ''.join(sys.argv[3:])
a = ''.join(sys.argv[2:])
s = ' '.join(sys.argv[1:])
flags = sys.argv[1:5]

commands = [["-r", "reverse string passed next with no quotes needed."], ["-j", "joins arguments passed into string. no quotes needed."], ["--palindrome", "tests whether arguments passed are palindrome or not. collective."],["--rand","passes random string of 10 digits/letters"]]

try:
    if "-r" in flags:
        if "-j" in flags:
            print mymodule.reverse(q)
        if not "-j" in flags:
            print mymodule.reverse(z)

    if "-j" in flags:
        if not "-r" in flags:
            print a

    if "--palindrome" in flags: mymodule.ispalindrome(z)

    if (not "-r" or not "-j" or not "--palindrome") in flags: mymodule.say(s)

    if "--rand" in flags: print(''.join([random.choice(string.ascii_letters+"123456789") for f in range(10)]))

    if not sys.argv[1]: print mymodule.no_arg_error

    if "--help" in flags: print commands

except: print mymodule.no_arg_error

i just want to be able to say

if "-r" and "-j" in flags in no particular order: do whatever

Anthropology

Answer 1

Also see getopt. It has a bit more terse syntax, and a complete example in docs.

Laminated

what do you mean by terse syntax? – Anthropology

With optparse, you generally add_option() for each option. With getopt, you just write something like options, fnames = getopt("abf:") and this handles -a, -b and -f filename. – Laminated

Answer 2

Something like

import optparse

p = optparse.OptionParser()
p.add_option('--foo', '-f', default="yadda")
p.add_option('--bar', '-b')
options, arguments = p.parse_args()

# if options.foo and options.bar ...

Stelu

what does "default" do? just curious how I would incorporate that – Anthropology

new to python, not programming – Anthropology

and optparse seems to be deprecated so i'll go with getopt? – Anthropology

p.add_option('--year', '-y', default='2011'). -> blah.py --year 2010. – Stelu

optparse is deprecated, but argparse is only introduced in 2.7. OS X, for example, runs 2.6 by default. If you are sure your audience is not on 2.6 anymore, you should go with argparse. Otherwise I'd recommend to stay with optparse, because it'll work on both 2.6 and 2.7. – Stelu

From the doumentation: "Deprecated since version 2.7: The optparse module is deprecated and will not be developed further; development will continue with the argparse module". getopt would be a step backwards. – Hertel

Answer 3

I'd recommend using argparse for this (or optparse if you're on Python 2.6.x or older).

Without a module you'd do this:

if "-r" in flags and "-j" in flags:
    do whatever

But I suggest you read the documentation for argparse and learn how to use it. You will be happy you did.

Pizza

i am unfamiliar with optparse and that's a reason. – Anthropology

Answer 4

'or' only can identify one,u should use 'a or b and c'

if (not "-r" or not "-j" and not "--palindrome") in flags: mymodule.say(s)

Xavier