Input Validator Abstraction

validator.py

from functools import wraps


def verify_inputs(filterers=None, validators=None):
    """ Verify the inputs going into any function with equal length lists of: 
        filterers (for filtering out objects we do not care about) and
        validators (to check the object itself is valid).
    """
    filterers = filterers if filterers is not None else []
    validators = validators if validators is not None else []

    def decorator(function):
        @wraps(function)
        def wrapper(*args, **kwargs):
            check_inputs = []
            for function_input in args + [v for k, v in iteritems(kwargs)]:
                for filterer in filterers:
                    if filterer(function_input):
                        check_inputs.append(function_input)

            for check_input in check_inputs:
                for validator, filterer in zip(validators, filterers):
                    if filterer(check_input):
                        validator(check_input)

            return function(*args, **kwargs)
        return wrapper
    return decorator

check out https://docs.python.org/2/library/functools.html#functools.wraps

Updated with functools.wraps implementation. I keep forgetting about that helpful little one. Gonna implement a bit better around validator/filter pairs now.

Added slightly better validation...still not convinced it's a great way to do it.