Nested namedtuples are way, way better than the proposed approach. I've found that nested dictionaries in Python are fragile in two dimensions: not only do you

Nested namedtuples are way, way better than the proposed approach. I've found that nested dictionaries in Python are fragile in two dimensions: not only do you have no guarantee that the values in your dictionaries are appropriately typed, you have no guarantee that the keys even exist! The whole thing just collapses in a messy heap if you look at it sideways. Furthermore, it's very hard to check to see whether anything has been changed deep within your crazy nested dictionary structure. With nested namedtuples, immutability lets you use "is" on the root to see whether anything has changed deep inside. Sure, you can't say foo.bar.baz.quux = 5, but did you really want to do that, knowing how hard it would be to use that information?