argparse - option with optional value

[Miki Tebeka]

Greetings,

I'd like to have an --edit option in my program. That if not specified will not open editor. If specified without value will open default editor ($EDITOR) and if specified with value, assume this value is the editor program to run.

The way I'm doing it currently is:
...
no_edit = 'no-edit'
parser.add_argument('-e', '--edit', help='open editor on log', nargs='?',
default=no_edit)
...
if args.edit != no_edit:
editor = args.edit or environ.get('EDITOR', 'vim')


However I get a feeling there's a better way to do that.
Any ideas?

Thanks,

 

[Miki Tebeka]

There is a built-in “no value specified” value in Python: the None

singleton. The ‘argparse’ library uses this for the argument default
already, so you don't need to fuss with your own special handling
<URL:http://docs.python.org/library/argparse.html#default>.

The problem with this approach is that in both cases of not specifying -e and with -e with no argument the value of args.edit is None.