How does this compare to schematics? It avoids inheritance, whereas in schematics and similar projects you'd have to inherit from their `Model` class (and thus acquire methods you might not want).
Until your comment, I had never seen schematics. I poked around a bit and my initial impression is that it seems like marshmallow-- it's heavily focused on validation rather than reducing boilerplate.
Schematics looks a bit like a less elegant version of schema. It does seem more focused on validation than attrs, I agree.
Schema [1] does not appear to have any support for object initialization.