Old-style class decorator example

class-decorator.py

def classdec(cls):
	def stat(itermeth):
		def inner(self):
			for i in itermeth(self):
				print "stat:", i
				yield i
		return inner
	cls.__iter__ = stat(cls.__iter__)
	return cls

class A(object):
	def __init__(self, x):
		self.x = x
	def __iter__(self):
		return iter(range(self.x))

A = classdec(A)
a = A(6)
for i in a:
	print i