Managing Deep Scope Hierarchies in Large Codebases
Article Summary
Uber rewrote their Android rider app in 2016 and made an architectural choice that most Android teams avoid: deeply nested dependency injection scopes.
This article from Uber Engineering explains why their old two-layer scope architecture couldn't scale and how they built a deep scope hierarchy to support hundreds of cities with varying features. They ultimately created RIBs, their own architectural framework, when existing options fell short.
Key Takeaways
- Old app's two-layer scope caused coupling, stale state, and hard-to-test code
- Deep scope hierarchies map controllers 1:1 with scopes, eliminating shared sibling data
- Evaluated MVC, VIPER, Flow, Conductor, and Scoop before building RIBs framework
- RIBs auto-generates scope boilerplate and decouples scopes from views
- Pattern enables static analysis for memory leaks and performance optimizations
Critical Insight
Deep scope hierarchies solved Uber's scaling problems by eliminating coupling between features and removing stale state through short-lived, well-encapsulated scopes.
