Function validated

Solutions/7_2/validate.py:64–99

(func)

    return isinstance(item, type) and issubclass(item, Validator)

def validated(func):
    sig = signature(func)

    # Gather the function annotations
    annotations = { name:val for name, val in func.__annotations__.items()
                    if isvalidator(val) }

    # Get the return annotation (if any)
    retcheck = annotations.pop('return', None)

    @wraps(func)
    def wrapper(*args, **kwargs):
        bound = sig.bind(*args, **kwargs)
        errors = []

        # Enforce argument checks
        for name, validator in annotations.items():
            try:
                validator.check(bound.arguments[name])
            except Exception as e:
                errors.append(f'  {name}: {e}')

        if errors:
            raise TypeError('Bad Arguments\n' + '\n'.join(errors))

        result = func(*args, **kwargs)

        # Enforce return check (if any)
        if retcheck:
            try:
                retcheck.check(result)
            except Exception as e:
                raise TypeError(f'Bad return: {e}') from None
        return result

    return wrapper

def enforce(**annotations):
    retcheck = annotations.pop('return_', None)