Chris Angelico wrote:
> On Thu, Feb 21, 2013 at 9:05 PM, Santosh Kumar <sntshkm...@gmail.com>
> wrote:
>> parser.add_argument(
>> 'install',
>> nargs='?',
>> help='install myapp'
>> )
>>
>> parser.add_argument(
>> 'uninstall',
>> nargs='?',
>> help='uninstall myapp'
>> )
>>
>> args = parser.parse_args()
>
> What you've done is make your program expect arguments, not options.
> Try running your script --help and you'll see how it parses. Whatever
> keyword is given goes into args.install, and if you provide a second
> arg, it'll become args.uninstall.
>
> To do what you're looking for there, I wouldn't bother with argparse
> at all - I'd just look at sys.argv[1] for the word you're looking for.
> Yes, it'd be a bit strict and simplistic, but by the look of things,
> you don't need sophistication.
>
> ChrisA
There's a simple way to use argparse
import argparse
def install():
print "installing"
def uninstall():
print "uninstalling"
def update():
print "updating"
actions = dict(install=install, update=update, uninstall=uninstall)
parser = argparse.ArgumentParser()
parser.add_argument("action", choices=actions)
args = parser.parse_args()
actions[args.action]()
that doesn't involve a lot of administrative overhead and allows you to add
options common to all "actions". Then there's the "right" way involving
subparsers
import argparse
def install(args):
print "installing"
def uninstall(args):
print "uninstalling"
def update(args):
print "updating"
actions = dict(install=install, update=update, uninstall=uninstall)
parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers()
for name, func in actions.iteritems():
p = subparsers.add_parser(name)
p.set_defaults(func=func)
args = parser.parse_args()
args.func(args)
which is still not too bad, although in a realistic application you'd have
to replace the for loop with individual blocks of code for every subparser.
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