@sgrif is working on a feature to enable registering custom column types in Active Record. For example, you will be able to register a
Money column type that is backed by an integer column in the database while exposing a more user-friendly API in Ruby. Future plans include refactoring existing features such as serialized attributes and enums using the foundation that is laid out in this change.
This pull request is currently waiting for more feedback from the core team. If you think you might have a use case for this feature, definitely take a look and see how well it'd work for your needs. (Avoid :+1: comments though, as they add very little to the conversation and create a lot of noise for everyone.)
While this feature is still waiting for further reviews, @sgrif already got serveral smaller refactoring merged into the codebase along the way.