google app engine - Detecting change in the value of python variables

Question

Is there some way to call a function each-time the value of a variable changes, in python?

Something like a listener, perhaps?

Specifically, I'm referring to the case where only the variable is shared between scripts like a GAE-Session. (Which uses Cookies, Memcache, etc to share data)

Example: ScriptA & ScriptB, share a session variable. When Script B changes it, SctiptA has to call a method to handle that change.

Answer 1

Waitting for answers