kwandl: Keyword arguments handled

Installation

To install kwandl from the GitHub repository, do:

git clone https://github.com/egpbos/kwandl.git
cd kwandl
python3 -m pip install .

Usage

kwandl is essentially a box of magic tricks to make working with kwargs smoother.

Passing only relevant kwargs

Say you have a function top which takes **kwargs and passes them on to ding and boop:

def top(**kwargs):
    ding(**kwargs)
    boop(**kwargs)

Only problem is: ding and boop have different sets of keyword arguments:

def ding(dingo=1, dinga=2):
    ...

def boop(boopie=3, boonk=4):
    ...

This means top(dingo="blurg", boonk=None) will fail with a TypeError, because boonk will be passed to ding and dingo will be passed to boop, both of which are invalid.

kwandl solves this for you with one simple decorator:

@kwandl.replace_kwargs_in_calls
def top(**kwargs):
    ding(**kwargs)
    boop(**kwargs)

This Just Works™.

It does so by modifying the abstract syntax tree (AST) of the function calls with kwargs as argument so that kwargs is effectively replaced by kwandl.get_kwargs_applicable_to_function(ding, kwargs) (or boop instead of ding depending on the calling function). An alternative way to use this kwandl functionality then is to use get_kwargs_applicable_to_function directly:

def top(**kwargs):
    ding(**kwandl.get_kwargs_applicable_to_function(ding, kwargs))
    boop(**kwandl.get_kwargs_applicable_to_function(boop, kwargs))

Note, however, that @kwandl.replace_kwargs_in_calls does a bit more: it also checks whether kwargs contains keyword arguments that are a match to neither ding nor boop and raises a TypeError if so. A complete alternative notation for @kwandl.replace_kwargs_in_calls would then be:

def top(**kwargs):
    ding_kwargs = kwandl.get_kwargs_applicable_to_function(ding, kwargs)
    boop_kwargs = kwandl.get_kwargs_applicable_to_function(boop, kwargs)

    unexpected_keywords = set(kwargs) - set(ding_kwargs) - set(boop_kwargs)

    if unexpected_keywords:
        raise TypeError(f"top() got an unexpected keyword argument '{unexpected_keywords.pop()}'")

    ding(**ding_kwargs)
    boop(**boop_kwargs)

The motivation behind this package should now become clearer: the amount of boilerplate necessary to solve what in my mind should not be such a huge problem is ... well, huge.

Documentation

For more details, see the full documentation on Readthedocs.

Contributing

If you want to contribute to the development of kwandl, have a look at the contribution guidelines.

Credits

This package was created with Cookiecutter and the NLeSC/python-template.