arguably 1.2.5

The best Python CLI library, arguably.

arguably turns functions and docstrings into command line interfaces (CLIs). arguably has a tiny API and is extremely easy to integrate. You can also use it directly through python3 -m arguably your_script.py, more on that here.

To use arguably in a script, decorate any functions that should appear on the command line with @arguably.command, then call arguably.run(). If multiple functions are decorated, they'll all appear as subcommands. You can even have multiple levels of subcommands: def s3__ls() becomes s3 ls.

#!/usr/bin/env python3
import arguably

@arguably.command
def some_function(required, not_required=2, *others: int, option: float = 3.14):
    """
    this function is on the command line!

    Args:
        required: a required argument
        not_required: this one isn't required, since it has a default value
        *others: all the other positional arguments go here
        option: [-x] keyword-only args are options, short name is in brackets
    """
    print(f"{required=}, {not_required=}, {others=}, {option=}")

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

becomes

user@machine:~$ ./intro.py -h
usage: intro.py [-h] [-x OPTION] required [not-required] [others ...]

this function is on the command line!

positional arguments:
  required             a required argument (type: str)
  not-required         this one isn't required, since it has a default value (type: int, default: 2)
  others               all the other positional arguments go here (type: int)

options:
  -h, --help           show this help message and exit
  -x, --option OPTION  keyword-only args are options, short name is in brackets (type: float, default: 3.14)

Arguments to the CLI look just like calling the Python function.

>>> from intro import some_function
>>> some_function("asdf", 0, 7, 8, 9, option=2.71)
required='asdf', not_required=0, others=(7, 8, 9), option=2.71

user@machine:~$ ./intro.py asdf 0 7 8 9 --option 2.71
required='asdf', not_required=0, others=(7, 8, 9), option=2.71

arguably uses your docstrings to automatically generate help messages. It supports all major formats for docstrings: reStructuredText, Google, Numpydoc, and Epydoc.

Type annotations are optional, but arguably can use them to automatically convert arguments. It has smart handling for mapping built-in types to the command line, including tuple, list, enum.Enum, and enum.Flag.

There are also a few special behaviors you can attach to a parameter via Annotated[] and the arguably.arg.* functions. Using arguably.arg.builder(), you can even build an object to pass in from the command line (using syntax inspired by QEMU):

user@machine:~$ ./build.py --nic tap,model=e1000 --nic user,hostfwd=tcp::10022-:22
nic=[TapNic(model='e1000'), UserNic(hostfwd='tcp::10022-:22')]

No integration required

Don't want to write any code? Simply pass any Python script to arguably to give it a command line interface.

user@machine:~$ python3 -m arguably party-trick.py -h
usage: party-trick [-h] [--version] command ...

this is the docstring for the whole script

positional arguments:
  command
    hello                   this is hello's docstring
    goodbye                 any function from a script can be called
    some-class              so can any __init__ for objects defined in the script
    some-class.func-static  a @staticmethod on a class can be called
    some-class.func-cls     so can a @classmethod

options:
  -h, --help                show this help message and exit
  --version                 show program's version number and exit

Installation

Install using pip install arguably. If you want to install using conda, please comment on this issue.

Documentation

• Why arguably?: https://treykeown.github.io/arguably/why/
• Examples: https://treykeown.github.io/arguably/examples/
• Tutorial: https://treykeown.github.io/arguably/tutorial/intro/
• API Reference: https://treykeown.github.io/arguably/api-reference/

Dependencies

All of arguably is built on top of argparse. It has two dependencies:

• docstring-parser for parsing function docstrings
• typing-extensions for Annotated[] support in Python 3.8 (only needed for that version)

Contributing

Ideas and help are very much appreciated! There's a guide for getting started with contributing to arguably that shows you how to run tests and pre-commit hooks.

• Contributing: https://treykeown.github.io/arguably/contributing/

Future roadmap

If you have any interest in these (either as a user or implementer), please leave a comment!

• #8 - Display all enum options in a command group
• #9 - Both positive and negative boolean flags
• #10 - Take inputs from environment variables
• #13 - Implement config interface
• #16 - Integration with rich for formatted CLI output