Overview

What is argbox?

argbox is a Python package for interacting with the arguments passed to a function by their respective parameter name or position in the function's signature:

Decorator example

import argbox

def my_decorator(func):
    def wrapper(*args, **kwargs):
        ctx = argbox.Context(func, args, kwargs) # (1)!
        param_0_arg = ctx.get_arg(position=0) # (2)!
        param_y_arg = ctx.get_arg(name="y") # (3)!
        print(f"Parameter 0={param_0_arg} y={param_y_arg}")
        return func(*ctx.args, **ctx.kwargs)
    return wrapper

@my_decorator
def func(x, y):
    pass

1. Create an context for a given function and passed arguments
2. Retrieve the argument corresponding to parameter with position 0
3. Retrieve the argument corresponding to the parameter with name 'y'

The decorated function behaves the same no matter if arguments are inputted as positional or keyword arguments; and no matter the ordering of the keyword arguments:

>>> func(10, 20)
10 20
>>> func(10, y=20)
10 20
>>> func(x=10, y=20)
10 20
>>> func(y=20, x=10)
10 20 # (1)!

1. Wait, shouldn't this print 20 20, since the 0th argument is now 20? No! The entire point ofargbox is to use the names and position of the parameters - not the passed arguments.

You can either use the core functionality of argbox, or some of the helper functions we have made for useful patterns such as dispatching or preprocessing functions.

Installation

The package is available on PyPI:

pip install argbox