Mine

class p(type):    def __init__(cls, name, bases, dict):        print 'init', name, dict        super(p, cls).__init__(name, bases, dict)    def __new__(cls, name, bases, dict):        print 'new', name, dict        return type(name, bases, dict)def px(name, bases, dict):    print 'px', name    return type(name, bases, dict)class Plugin(object):    __metaclass__ = p    x = 3print Plugin, Plugin.x# in your plugin modulesclass SpamPlugin(Plugin):    x = 1print SpamPlugin, SpamPlugin.xclass BaconPlugin(Plugin):    pass