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Argh

The goal

Argh helps to handle command line arguments in a big way. Don’t use the build-in Python stuff for that.

Questions to David Rotermund

pip install argh

Simple example

No argument is required​

The arguments are now only optional for the function call:

import argh


def main(first_parameter: int = 1, second_parameter: int = 2, third_parameter: bool = True) -> None:
    print("Main")


if __name__ == "__main__":
    argh.dispatch_command(main)

python test.py

Output

Main

python test.py --help

Output

usage: test.py [-h] [-f FIRST_PARAMETER] [-s SECOND_PARAMETER] [-t]

options:
  -h, --help            show this help message and exit
  -f FIRST_PARAMETER, --first-parameter FIRST_PARAMETER
                        1
  -s SECOND_PARAMETER, --second-parameter SECOND_PARAMETER
                        2
  -t, --third-parameter
                        True

Note: For boolean parameters using the option switches them to the other state. Here python test.py sets third-parameter=True and python test.py -t sets third-parameter=False.

One argument is required​

import argh


def main(first_parameter: int, second_parameter: int = 2, third_parameter: bool = True) -> None:
    print("Main")


if __name__ == "__main__":
    argh.dispatch_command(main)

python test.py

Output

usage: test.py [-h] [-s SECOND_PARAMETER] [-t] first-parameter
test.py: error: the following arguments are required: first-parameter

python test.py 1

Output

Main

More than one function​

Sometimes we have a collection of function. This is how we select one of those:

import argh


def main_1(
    first_parameter: int = 1, second_parameter: int = 2, third_parameter: bool = True
) -> None:
    print("Main 1")


def main_2(first_parameter: int = 1) -> None:
    print("Main 2")


if __name__ == "__main__":
    parser = argh.ArghParser()
    parser.add_commands([main_1, main_2])
    parser.dispatch()

python test.py

Output

usage: test.py [-h] {main-1,main-2} ...

python test.py main-1
python test.py main-2

Output:

Main 1
Main 2

python test.py main-1 --help
python test.py main-2 --help

Output:

usage: test.py main-1 [-h] [-f FIRST_PARAMETER] [-s SECOND_PARAMETER] [-t]

options:
  -h, --help            show this help message and exit
  -f FIRST_PARAMETER, --first-parameter FIRST_PARAMETER
                        1
  -s SECOND_PARAMETER, --second-parameter SECOND_PARAMETER
                        2
  -t, --third-parameter
                        True

usage: test.py main-2 [-h] [-f FIRST_PARAMETER]

options:
  -h, --help            show this help message and exit
  -f FIRST_PARAMETER, --first-parameter FIRST_PARAMETER
                        1

Reference

The source code is Open Source and can be found on GitHub.