Developing with the interactive interpreter can be tricky. When your class changes, you need to reload the module and create new objects with the new code.
This recipe offers a simple wrapper which will make reloading a bit easier.
Python, 53 lines
As written, this wrapper simply replaces the old object with a fresh new one. None of the old state is saved. Copying of state from the old object to the new one could be added.
Other solutions involve metaclasses (http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/160164) or a background watcher thread (http://aspn.activestate.com/ASPN/Mail/Message/python-list/907876)