kwargs-only

---

Unmaintained: I'm no longer maintaining this package because it's for Python 2 compatibility and all other projects I've used it on are now Python 3 only. If you want to continue maintenance please contact me.

---

A decorator to make a function accept keyword arguments only, on both Python 2 and 3.

If you are using only Python 3, you don't need this, you can just do:

def myfunction(*, foo=1, bar=2):
    pass

Why?

If you are making a library (that still supports Python 2), you might want to make all functions in its API take keyword arguments only, for a couple of reasons:

• To avoid user confusion, e.g. if you take x and y arguments as coordinates, it's easy to forget which way round to pass them.
• To make your API easier to extend - you'll know no callers rely on the positional argument ordering, so can refactor this to make sense.

Installation

Use pip:

pip install kwargs-only

Python 2.7 and 3.4 to 3.8 supported.

Usage

Import the decorator and apply it to a function:

from kwargs_only import kwargs_only

@kwargs_only
def myfunction(foo=1, bar=2):
    pass

Then calling the function with positional arguments will cause it to fail with TypeError:

>>> myfunction(1, 2)
...
TypeError: myfunction should only be called with keyword args

The decorator detects methods and classmethods, by allowing for the first argument to be a positional one if its name is self or cls. kwargs_only should be applied to the function before classmethod is. For example:

class MyClass:

    @classmethod
    @kwargs_only
    def my_class_method(cls, foo=1):
        pass

    @kwargs_only
    def my_instance_method(self, bar=1):
        pass

That's about all there is to it! Enjoy!