func-argparse

func_argparse

Generate a nice command line interface for a list of functions or a module, leveraging your doc-strings and type annotations. Never worry about your Argparser being out of sync with your code. Try it with pip install func_argparse.

Example

In a 'hello.py' file:

"""Say hello or goodbye to the user."""

import func_argparse


def hello(user: str, times: int = None):
    """Say hello.

    Arguments:
        user: name of the user
    """
    print(f"Hello {user}" * (1 if times is None else times))


def bye(user: str, see_you: float = 1.0):
    """Say goodbye."""
    print(f"Goodbye {user}, see you in {see_you:.1f} days")


if __name__ == "__main__":
    func_argparse.main()

From CLI:

$ python hello.py hello --user gwenzek
Hello gwenzek

$ python hello.py hello --user gwenzek --times 2
Hello gwenzekHello gwenzek

$ python hello.py bye --user gwenzek --see_you 12.345
Goodbye gwenzek, see you in 12.3 days

$ python hello.py hello -u gwenzek -t 1
Hello gwenzek

$ python hello.py --help
usage: hello.py [-h] {hello,bye} ...

Say hello or goodbye to the user.

positional arguments:
  {hello,bye}
    hello      Say hello.
    bye        Say goodbye.

optional arguments:
  -h, --help   show this help message and exit

$ python hello.py bye --help
usage: hello.py bye [-h] -u USER [-s SEE_YOU]

optional arguments:
  -h, --help            show this help message and exit
  -u USER, --user USER
  -s SEE_YOU, --see_you SEE_YOU
                        (default=1.0)

Gotchas

• func_argparse generate classics argparse.Argparser you can mix and match them with hand-written parsers.
• func_argparse.main() create one CLI command by "public" function from a file / module.
• Use func_argparse.single_main(my_main) if you only have one entry point in your file.
• All functions arguments need a type hint.
• Arguments without default value will be marked as required.
• A boolean argument a will generate two flags: --a and --no-a.
• A boolean argument with no default value will be assumed to default to False.
• The first argument starting with letter a will also be available with the flag -a.
• The function docstring will be parsed to extract the help messages.
  • First line is used as help message for the function
  • First line starting with a will be used to extract the documentation for argument a. Spaces, dashes and columns will be stripped before displaying.
• Some kind of functions (notably builtin and C-function) can't be inspected and we can't generate Argparser for them.
• You can't have a function with an argument named __command when using main or multi_parser.
• If you don't like the generated parser, you can modify it using override function.

Alternatives

Here are other alternatives you might be interested in.

• argparse: the builtin library upon which func_argparse is built. Grants a very precise control on the CLI but is a bit verbose and prone to go out-of-sync with the code.
• fire: also generates parser with introspection but doesn't leverage types. So the types of arguments is determined at parse time. Can generate completion files.
• click: uses function annotations to generate the CLI.

Contibuting

All contributions are welcome. Code formatting is enforced with isort, black. Types annotations are required for the main module and checked with mypy. Tests are run with pytest.

Run pip install ".[dev]" to install the required modules Run ./tools.sh all to format your code and run mypy and pytest.

TODOs

• Add all parameters from add_argument to override
• Chose one from Circle CI and Github Workflows
• Make it easy to parse a comma separated list of argument