Docopt - Multiple values for an optional argument

Question

I would like to parse an optional argument with multiple values with docopt. Below is the example usage.

my_program.py --loc pcg acc
# or anything that achieve similar result

and after parsing, I expect that to have a python list like so

arguments["--loc"] = ["pcg", "acc"]

I browsed around and found out if this is doable in argparse by passing nargs argument.

I couldn't find any similar way in docopt, is this doable in docopt? If not, what's the alternative?

An alternative that I can think of is to ask user specify value separated by comma and manually split it during parsing as below.

my_program.py [--loc=<comma_separated_str>]

In the python code

locs = arguments["--loc"].split(",") if arguments["--loc"] else []

However, that seems ugly, so I'm looking for a proper way to do so with docopt.

Answer 1

The definition you are looking for is probably

"""
Usage: my_program.py --help
   my_program.py [(--loc <loc>) [<loc>...]]
"""

from docopt import docopt
print(docopt(__doc__))

Multiple --loc values are provided with spaces between them

python3 my_program.py --loc pcg acc hah
{'--help': False,
 '--loc': True,
 '<loc>': ['pcg', 'acc', 'hah']}

The --loc argument is indeed optional

$ python3 my_program.py
{'--help': False,
 '--loc': False,
 '<loc>': []}

Providing no values for --loc results in an error

$ python3 my_program.py --loc
Usage: my_program.py --help
       my_program.py [(--loc <loc>) [<loc>...]]

If --loc could be used without any value, this simpler definition will do

"""
Usage: my_program.py --help
       my_program.py [--loc <loc> ...]
"""

from docopt import docopt
print(docopt(__doc__))

resulting in

$ python3 my_program.py --loc
{'--help': False,
 '--loc': True,
 '<loc>': []}

It is otherwise equivalent to the first definition