A decorator that enforces a particular type/subtype for each parameter of a function

enforced_parameters_decorator.py

class enforce(object):
	def __init__(self,*argtypes):
		# the types that need to be enforced for each position arg[i]
		self.argtypes = argtypes

	def __call__(self,f):
		def wrapper(*args):
			# bail if the definition isn't set up to handle this many arguments
			if len(self.argtypes) < len(args):
				raise Exception('too many parameters passed in')
			for i in range(len(args)):
				#test if arg[i] is not the class/subclass for this position
				if not issubclass(args[i].__class__, self.argtypes[i]):
					t_arg = self.argtypes[i].__name__
					raise Exception('arg %d type %s invalid, should be %s' % (i, args[i].__class__, t_arg))
			return f(*args)
		return wrapper

#example function
@enforce(int)
def foo(n):
	print('n = %d' % n)

#example useage
foo(5)
foo('Hi')