How to redefine object so that all user- objects have the necessary capabilities?

[AlekseyPython]

Could you post short code exemplifying what you're talking about?

Also, if you haven't heard already, pickle is typically considered a security hole, so you might want to consider JSON or something else for your serialization. That won't directly help you with saving class variable though, I suspect that's something you'll just have to do manually.

json has limitations:
a) tuple during serialization / deserialization transform into a list.
b) what happens with set- it's unknown.
c) dict keys should ONLY have the string / number type.

Therefore, this method does not allow writing arbitrary code.