aarghparse

========== aarghparse

Motivation

I was having shower and this name came up.

At the moment this is a collection of argparse_ extensions I have written and found useful in recent times.

.. But really I want an argparse-based argument parser which is able to load plugins based on parsed arguments and let those plugins define additional arguments. I have made this work for one of my clients, but it's dirty.

Features

• @arg_converter decorator to write simple argument value parsers without the argparse.Action boilerplate
• @subcommand decorator to save you from all the add_subparsers and set_defaults(func=).
• @cli decorator to generate a command-line interface.

.. The dynamic loader mentioned in the Motivation_ isn't available yet.

.. _argparse: https://docs.python.org/3/library/argparse.html

Example

The example below combines all the features, but the tool doesn't enforce it on you.

If you have an existing argparse.ArgumentParser definition, you should be able to replace it with aarghparse by just changing the initialisation line to parser = aarghparse.ArgumentParser(...).

.. code-block:: python

import datetime as dt

import dateutil.tz

from aarghparse import ArgumentParser, arg_converter, cli


@cli
def calendar_cli(parser: ArgumentParser, subcommand: ArgumentParser.subcommand):
    """
    Command-line calendar.
    """

    parser.add_argument(
        '--date-format',
        default=None,
    )

    @arg_converter
    def tz_arg(value):
        return dateutil.tz.gettz(value)

    @subcommand(
        name="now",
        args=[
            ["--tz", {
                "action": tz_arg,
                "help": "Timezone",
            }],
        ],
    )
    def now_cmd(args):
        """
        Prints today's date.
        """
        date_format = args.date_format or "%Y-%m-%d %H:%M:%S"
        print(dt.datetime.now(tz=args.tz).strftime(date_format))


if __name__ == "__main__":
    calendar_cli.run()

If you install python-dateutil then you can try the above with:

.. code-block:: shell

python -m aarghparse.examples.calendar --help
python -m aarghparse.examples.calendar now --help
python -m aarghparse.examples.calendar now --tz "Europe/Riga"
python -m aarghparse.examples.calendar --date-format "%d.%m.%Y." now --tz "Europe/Riga"