type_check.py

#!/usr/bin/env python3
# vim: set noexpandtab:
from functools import wraps
from inspect import signature

def type_checked(func):
	@wraps(func)
	def wrapper(*args, **kwargs):
		sig = signature(func)
		bound = sig.bind(*args, **kwargs)
		for k,v in bound.arguments.items():
			ann = sig.parameters[k].annotation
			if ann and not isinstance(v, ann):
				raise ValueError("Argument {} should be of type {}, is {}"
					.format(k, ann, type(v)))
		return func(*bound.args, **bound.kwargs)
	return wrapper