[theptip]

The point is that for data-bag style classes, you end up writing a lot more boilerplate than that if you use them across a project. Validators (type or content), nullable vs not, read-only, etc.

The minimal trivial case doesn’t look much different, but if you stacked up 10 data classes with read-only fields vs. bare class implementations with private members plus properties to implement read-only, and you would start to see a bigger lift from attrs, as there would be a bunch of boring duplicated logic.

(Or not - if your usecases are all trivial then of course don’t use the library for more complex usecases. But hopefully you can see why this gets complex in some codebases, and why some would reach for a framework.)