parameter-checks 1.0.0

Extend typehints to include dynamic checks (that might otherwise be dealt with by assertions) in Python.

For more info, please visit the GitHub page of this project.

Basic example

import parameter_checks as pc


@pc.hints.cleanup   # be left with only type-annotations
@pc.hints.enforce   # enforce the lambda but not the types
def div(a: int, b: pc.annotations.Checks[int, lambda b: b != 0]):
    return a / b 

div(1, 1)   # returns 1.0
div(1, 0)   # raises ValueError

As can be seen in this example, this package provides a new type-annotation: pc.annotations.Checks (it also provides pc.annotations.Hooks, see below). Using @pc.hints.enforce on a function will enforce the checks given to those annotations (but not the types). @pc.hints.cleanup would produce the div.__annotations__ of {"a": int, "b": int} in the example above.

Complex example

import parameter_checks as pc


def decision_boundary(fct, parameter, parameter_name, typehint):
    if type(parameter) is not typehint:
        err_str = f"In function {fct}, parameter {parameter_name}={parameter} " \
                  f"is not of type {typehint}!"
        raise TypeError(err_str)
    
    return 3 + 4 * parameter - parameter ** 2


@pc.hints.enforce
def classify(
        x: pc.annotations.Hooks[float, decision_boundary],
        additional_offset: pc.annotations.Checks[float, lambda b: 0 <= b <= 100] = 0.
) -> bool:
    return (x + additional_offset) >= 0
    

if __name__ == '__main__':
    assert classify(1.) is True   # 6.
    assert classify(2.) is True   # 7.
    assert classify(5.) is False   # -2.
    assert classify(5., 2.) is True   # 0.
    
    classify("not a float!")  # raises TypeError
    classify(1., -1.)   # raises ValueError

For additional comments on this example (and much more), visit the GitHub page of this project.