defopt
======
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| |Read the Docs| |Build|
.. |GitHub|
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.. |PyPI|
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.. |conda-forge|
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.. |Read the Docs|
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:target: `Read the Docs`_
.. |Build|
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defopt is a lightweight, no-effort argument parser.
defopt will:
- Allow functions to be run from code and the command line without modification.
- Reward you for documenting your functions.
- Save you from writing, testing and maintaining argument parsing code.
defopt will not:
- Modify your functions in any way.
- Allow you to build highly complex or customized command line tools.
If you want total control over how your command line looks or behaves, try
docopt_, click_ or argh_. If you just want to write Python code and leave the
command line interface up to someone else, defopt is for you.
Usage
-----
Once you have written and documented_ your function, simply pass it to
`defopt.run()` and you're done.
.. code-block:: python
import defopt
# Use type hints:
def main(greeting: str, *, count: int = 1):
"""
Display a friendly greeting.
:param greeting: Greeting to display
:param count: Number of times to display the greeting
"""
for _ in range(count):
print(greeting)
# ... or document parameter types in the docstring:
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] [-c COUNT] greeting
Display a friendly greeting.
positional arguments:
greeting Greeting to display
optional arguments:
-h, --help show this help message and exit
-c COUNT, --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:
#. **The interface can be fully understood in seconds.** If it took any longer,
your time would be better spent learning a more flexible tool.
#. **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.
#. **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.
#. **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`_.
.. _GitHub repository: https://github.com/anntzer/defopt
.. _Read the Docs: https://defopt.readthedocs.io/en/latest/
.. _autodoc: http://www.sphinx-doc.org/en/stable/ext/autodoc.html
.. _docopt: http://docopt.org/
.. _click: http://click.palletsprojects.com/
.. _argh: https://argh.readthedocs.io/en/latest/
.. _documented: https://defopt.readthedocs.io/en/latest/features.html#docstring-styles
.. This document is included in docs/index.rst; table of contents appears here.