List of arguments with argparse

Question

I'm trying to pass a list of arguments with argparse but the only way that I've found involves rewriting the option for each argument that I want to pass:

What I currently use:

main.py -t arg1 -a arg2

and I would like:

main.py -t arg1 arg2 ...

Here is my code:

parser.add_argument("-t", action='append', dest='table', default=[], help="")

Answer 1

Use nargs:

ArgumentParser objects usually associate a single command-line argument with a single action to be taken. The nargs keyword argument associates a different number of command-line arguments with a single action.

For example, if nargs is set to '+'

Just like '*', all command-line args present are gathered into a list. Additionally, an error message will be generated if there wasn’t at least one command-line argument present.

So, your code would look like

parser.add_argument('-t', dest='table', help='', nargs='+')

That way -t arguments will be gathered into list automatically (you don't have to explicitly specify the action).

Answer 2

Being aware, you asked for argparse solution, I would like to present alternative solution using package docopt

Install it first:

$ pip install docopt

Write the code:

"""Usage:
    main.py -a <arg>...
"""

if __name__ == "__main__":
    from docopt import docopt
    resargs = docopt(__doc__)
    print resargs

Run it to show usage instrucitons:

$ python main.py
Usage:
    main.py -a <arg>...

Call it with your parameters:

$ python main.py -a AA BB CC
{'-a': True,
 '<arg>': ['AA', 'BB', 'CC']}

Btw. if you do not need the -a option, you shall directly allow passing the arguments. It makes usage simpler to the user.