Nick Falco Nick Falco - 20 days ago 6
Python Question

Python argparse with -- as the value

NOT A DUPLICATE -- This question is different than "Having options in argparse with a dash" since I am passing -- as the value to an argument, not as the argument.

Is there a way to pass -- as a value to a Python program using argparse without using the equals (=) sign?

The command line arguments that I added to the argparser are defined like below:

parser.add_argument('--myarg', help="my arg description")


You would use this argument in a program like this:

python myprogram.py --myarg value123


Is there a way to run this program with -- as the value instead of 'value123'?

i.e

python myprogram.py --myarg --

wim wim
Answer

I suspect it will not be possible to make argparse do this natively. You could pre-process sys.argv though, as a non-intrusive workaround.

import sys
from argparse import ArgumentParser
from uuid import uuid4

sentinel = uuid4().hex

def preprocess(argv):
    return [sentinel if arg == '--' else arg for arg in argv[1:]]

def postprocess(arg):
    return '--' if arg == sentinel else arg

parser = ArgumentParser()
parser.add_argument('--myarg', help="my arg description", type=postprocess)
args = parser.parse_args(preprocess(sys.argv))