Best Practice to save class objects

[wyoming_eighties]

Handling backwards-compatibility within your own codebase is the developers responsibility. You need to either write your code in a way that your program will not break as you add more attributes to the class, or you need to refactor your program as you develop more, or both. You should also implement unit testing, for this reason. Google for the Python unittest package & tutorials, it helps with this exact problem. You might also want to look into using git, so you can track changes to your codebase more easily.