Chapter29 (v1) Modular programming using objects
Chapter29 (v2) Modular programming: The problem
Chapter29 (v3) Modular programming: Application design
Chapter29 (v4) Modular programming: Abstraction
Chapter29 (v5) Modular programming (source)
Chapter29 (v6) Modular programming: Splitting modules into traits
Chapter29 (v7) Splitting modules into traits (source)