duckargs 1.2.0

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

duckargs 🦆

The purpose of duckargs 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

Install with pip (python 3x required):

pip install duckargs

Example

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 -F --otherfile FILE -a -b -c

The output of the above command looks like this:

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

import argparse

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

    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=None, type=argparse.FileType(), help='a filename')
    parser.add_argument('-F', '--otherfile', default=None, 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()

    print(args.positional_arg1)
    print(args.positional_arg2)
    print(args.int_val)
    print(args.f)
    print(args.file)
    print(args.otherfile)
    print(args.a)
    print(args.b)
    print(args.c)

if __name__ == "__main__":
    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')

Filenames for option arguments

If you have an option that you want to accept a filename, you have two ways to tell duckargs that the option argument should be treated as a file:

• Pass the path to a file that actually exists (e.g. -f --filename file.txt) as the option argument

• Pass FILE as the option argument (e.g. -f --filename FILE)

Either of which will generate a line like this:

parser.add_argument('-f', '--filename', default='file', 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)

Pitfalls

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)

Contributions

Contributions are welcome, please open a pull request at https://github.com/eriknyquist/duckargs/pulls and ensure that all existing tests pass, and new test(s) are added if required (run tests via python setup.py test).

If you have any questions about / need help with contributions or tests, please contact Erik at [e-mail].