defopt 3.1.1

Usage

Once you have written and documented your function, simply pass it to defopt.run() and you’re done.

import defopt

def main(greeting, count=1):
    """Display a friendly greeting.

    :param str greeting: Greeting to display
    :param int count: Number of times to display the greeting
    """
    for _ in range(count):
        print(greeting)

if __name__ == '__main__':
    defopt.run(main)

Descriptions of the parameters and the function itself are used to build an informative help message.

$ python test.py -h
usage: test.py [-h] [--count COUNT] greeting

Display a friendly greeting.

positional arguments:
  greeting       Greeting to display

optional arguments:
  -h, --help     show this help message and exit
  --count COUNT  Number of times to display the greeting (default: 1)

Your function can now be called identically from Python and the command line.

>>> from test import main
>>> main('hello!', count=2)
hello!
hello!

$ python test.py hello! --count 2
hello!
hello!

Philosopy

defopt was developed with the following guiding principles in mind:

1. The interface can be fully understood in seconds. If it took any longer, your time would be better spent learning a more flexible tool.

2. Anything you learn applies to the existing ecosystem. The exact same docstrings used by defopt are also used by Sphinx’s autodoc extension to generate documentation, and by your IDE to do type checking. Chances are you already know everything you need to know to use defopt.

3. Everything is handled for you. If you’re using defopt, it’s because you don’t want to write any argument parsing code at all. You can trust it to build a logically consistent command line interface to your functions with no configuration required.

4. Your Python functions are never modified. Type conversions are only ever applied to data originating from the command line. When used in code, duck-typing still works exactly as you expect with no surprises.

Development

For source code, examples, questions, feature requests and bug reports, visit the GitHub repository.

Documentation

Documentation is hosted on Read the Docs.