typecorrector 0.2.1

A decorator meant to give type hints about function parameters as well as allow a margin of error

Intro

Type corrector is module that contains the decorator type_corrector. This decorator lets the user specify what types the arguments to a function should have. It’s not 100% safe to use as it might result in a ValueError or TypeError if the user is not careful enough. The motivation behing this module was to find a way that makes it easier for the programmer to see what types the arguments should be, and at the same time allow some margin of error. I’m not sure if this is a good idea, or if it’s a good approach. It was mostly developed for fun while playing around with decorators.

Installation

pip install typecorrector

Usage

First import type_corrector from typecorrector:

from typecorrector import type_corrector

Then you can decorate your functions with type_corrector

@type_corrector(int, int)
def add(x,y):
    return x+y


@type_corrector(float, float)
def div(x,y):
    return x/y

A call to add(1,’2’) will cast ‘2’ to an int, since that is what we specified as the type of the second paramater in the decorator. We can also call div as div(‘10’, ‘3’), and div will return 3.3333333333333335 as expected.

This decorator also works with *args and **kwargs

@type_corrector(int)
def mult(*numbers):
    result = 1
    for num in numbers:
        result *= num
    return result

@type_corrector(int)
def kw_mult(**kwargs):
    first = kwargs.get('first')
    second = kwargs.get('second')
    third = kwargs.get('third')
    return first * second * third

This allows us to call the functions like this: mult(‘2’, ‘3’, ‘4’) kw_mult(first=’2’, second=’3’, third=’3’)

By looking at the function definitions we can still see that the both parameters of add are supposed to be integers and mult and kw_mult also work with integers. By decorating the functions this it should be a clear hint what types we want to operate with, even though it allows some margin of error.

Known issues

When calling help on a decorated function the parameters are not shown correctly, instead it will just say <function name>(*args, **kwargs) Also, when using inspect to get the argument specification with inspect.getargspec or getting the source code from inspect.getsourcelines it will fail. Thanks to the functools.wraps decorator the docstring of a wrapped function will still shown correctly.