Productivity tool for quickly creating python programs that parse command-line arguments. Stop writing argparse boilerplate code!

eriknyquist eriknyquist Last update: Aug 06, 2023


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The purpose of this package is to save some typing whenever you want to quickly create a python program that accepts command line arguments. Just run duckargs with the arguments that you want your program to accept, with example values for options, and duckargs will generate the python code for a program that uses argparse to handle those arguments.


Install with pip (python 3x required):

pip install duckargs


Run duckargs from the command line via python -m duckargs, followed by whatever arguments/options/flags you want your program to accept, and duckargs will print the corresponding python code.

$ python -m duckargs positional_arg1 positional_arg2 -i --int-val 4 -f 3.3 -F --file file_that_exists -a -b -c >

After running the above command, the file will contain the following code:

# positional_arg1 positional_arg2 -i --int-val 4 -f 3.3 -F --file file_that_exists -a -b -c

import argparse

def main():
    parser = argparse.ArgumentParser(description='',

    parser.add_argument('positional_arg1', help='a string')
    parser.add_argument('positional_arg2', help='a string')
    parser.add_argument('-i', '--int-val', default=4, type=int, help='an int value')
    parser.add_argument('-f', default=3.3, type=float, help='a float value')
    parser.add_argument('-F', '--file', default='file_that_exists', type=argparse.FileType(), help='a filename')
    parser.add_argument('-a', action='store_true', help='a flag')
    parser.add_argument('-b', action='store_true', help='b flag')
    parser.add_argument('-c', action='store_true', help='c flag')
    args = parser.parse_args()


if __name__ == "__main__":

Comma-separated choices for option argument

If you have an option which accepts an argument, and you write an argument string with multiple values separated by commas (e.g. -m --mode active,idle,sim), then duckargs will use the comma-separated values as a choices list for argparse, e.g.:

parser.add_argument('-m', '--mode', choices=['active', 'idle', 'sim'], default='active', help='a string')

Real filename for option argument

If you have an option which accepts an argument, and the argument string that you write happens to be the path to a file that actually exists (e.g. -f --filename real_file.txt), then duckargs will tell argparse that this argument is a file, e.g.:

parser.add_argument('-f', '--filename', default='real_file.txt', type=argparse.FileType(), help='a filename')

Use duckargs in python code

If you want to use duckargs in your own script, you can use the duckargs.generate_python_code function, which accepts a list of command line arguments:

import sys
from duckargs import generate_python_code

python_code = generate_python_code(sys.argv)


If you have a combination of flags and positional arguments, and you happen to have a flag followed by a positional argument (as in: python -m duckargs -q --quiet positional_arg), duckargs has no way to tell that you wanted a positional arg, so it will assume you want an option -q --quiet with a required argument.

To avoid this, it is recommended to declare your positional arguments first (as in: python -m duckargs positional_arg -q --quiet)

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