IMHO there's quite a difference between what's technically inheritance in an ORM (I am assuming you mean writing "class MyModel(orm.model):", not in-database-in

IMHO there's quite a difference between what's technically inheritance in an ORM (I am assuming you mean writing "class MyModel(orm.model):", not in-database-inheritance) and Java'esque tree hierarchies of classes. The former is mostly about invoking a type operator / metaclass [1] to construct a model class from your declarative specification. I don't know what the latter is about. I think deep inheritance (where deep means like "more than 2") are virtually always a mistake. Stuff like toolkits that go Object>Widget>AbstractButton>PushButton might be an exception but I'm not entirely sure, there's probably a better way. [1] I think metaclasses aren't type operators in the strict sense, because they're not handed a finished type, but rather the declaration of a type, and then create a type. Maybe there's a word for that.