How to combine multiple values for an argument using argparse

Question

I'm using argparse to make a command line tool for my work.
I have a requirement wherein an argument should be able to take multiple values.

The argument can take only legal values.

The legal values can be any combination of values coming from a list, "ALL".

sample.py:

import argparse

sample_list = ["a", "b", "c"]

parser = argparse.ArgumentParser()

parser.add_argument('-M', '--Module', choices=sample_list, default=default_module, help='specify the Module name')
args = parser.parse_args()

Using the above approach the allowed values the allowed values are:

python sample.py -M a

I want that user is able to enter:

python sample.py -M a,b
<ok>

python sample.py -M ALL
<ok>

python sample.py -M D
<error>

How to achieve this?

Try refer to http://stackoverflow.com/questions/8526675/python-argparse-optional-append-argument-with-choices — Desmond Lua, Oct 23 '15 at 10:52
You could implement a custom `type` function for that argument, which would check against `sample_list` per your rules, but there's no built-in way to do it AFAIK — jonrsharpe, Oct 23 '15 at 11:00

score 0 · Answer 1 · answered Oct 23 '15 at 18:00

The simplest solution would be to include ALL is the list of allowable choices, and use either action='append' or nargs='*' to accept multiple values. I'd leave the interpretation of ALL to post-parsing code.

As has been discussed in other SO questions, trying to handle comma delimited sublists is a pain.

How to combine multiple values for an argument using argparse

1 Answers1