1. Motivation

• "Cartesian product" complexity explosion
• E.g. ThreadScheduler that can run on Windows or Unix
• End up 2x2- WindowsPTS, UnixPTS, WindowsCTS, UnixCTS
• It decouples interface (hierarchy) for an implementation (hierarchy)

2. Bridge

• circle square
• vector raster
• Goal escape complexity by connecting hierarchy to two classes.
• It is still not very good in terms of Open close principles

3. Summary

• Decouple abstraction for implementation
• Stronger form of encapsulation