Python: keeping track of info across classes by storing a variable to self
I think what you may be looking for is the Borg design pattern. It's meant for a single class to maintain state between multiple instances. Not exactly what you're looking for but you could modify it to also maintain state across multiple classes, perhaps by specifying a global for shared state:

## {{{ http://code.activestate.com/recipes/66531/ (r2)
class Borg:
    __shared_state = {}
    def __init__(self):
        self.__dict__ = self.__shared_state
    # and whatever else you want in your class -- that's all!
## end of http://code.activestate.com/recipes/66531/ }}}


Here are some links to various code examples of this, non chronological:


Python borg pattern problem
Singleton? We don't need no stinkin' singleton: the Borg design pattern (Python recipe)
Usage example