Metaclass example

gistfile1.py

class WooMeta(type):
    def __init__(cls, name, bases, attrs):
        names = [n for n in attrs.keys() if not n.startswith('_')]
        cls._attributes = tuple(names)
        super(WeeMeta, cls).__init__(name, bases, attrs)

class Wee(object):
    __metaclass__ = WooMeta
    foo = 1
    zoo = 2

class Person(Wee):
    name = "john"
    age = 10

assert Wee._attributes == ('foo', 'zoo'), \
       'Expected tuple("foo", "zoo"), got %s' % repr(Wee._attributes)
assert Person._attributes == ('age', 'name'), \
       'Expected tuple("age", "name"), got %s' % repr(Person._attributes)