Dynamic Type Checking

checking.py

#!/usr/bin/python

import inspect

def typeAsserting(f):
    signature = inspect.signature(f)
    def wrapper(*args, **kwargs):
        bound_args = signature.bind(*args, **kwargs)
        for name, parameter_value in bound_args.arguments.items():
            expected_type = signature.parameters[name].annotation
            if not isinstance(parameter_value, expected_type):
                actual_type = type(parameter_value)
                raise TypeError("Paramter '{name}={parameter_value}' has type {actual_type} instead of expected type {expected_type}.".format(**locals()))
        return_value = f(*bound_args.args, **bound_args.kwargs)
        expected_type = signature.return_annotation
        if not isinstance(return_value, signature.return_annotation):
            actual_type = type(return_value)
            raise TypeError("Return value '{return_value}' has type {actual_type} instead of expected type {expected_type}.".format(**locals()))
        return return_value
    return wrapper

def typeConverting(f):
    signature = inspect.signature(f)
    def wrapper(*args, **kwargs):
        bound_args = signature.bind(*args, **kwargs)
        for name, val in bound_args.arguments.items():
            bound_args.arguments[name] = signature.parameters[name].annotation(val)
        return signature.return_annotation(f(*bound_args.args, **bound_args.kwargs))    
    return wrapper