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📜 WAYPOINT LESSON

Smells & Refactoring

⭐⭐ intermediate⏳ 14 min read📍 Lesson 115 of 180

Long methods, primitive obsession, feature envy — and comments that explain why instead of what.

Code smells and the refactoring reflex

Smells don't prove a bug — they invite a look:

  • Long method — many blank lines and levels; extract methods
  • Primitive obsession — money as int, phone as String everywhere; introduce tiny value types
  • Data clumps — city, street, zip traveling together forever; make an Address record
  • Feature envy — a method reaching into another object's getters more than its own fields; move it there
  • Shotgun surgery — one change touches ten files; the concept needs a home
  • Comment explaining WHAT — the code should say what; comments say why (constraints, links, tradeoffs)
// before — primitive obsession + long method
static boolean ok(String u, String p) { ... }

// after — names and types carry the design
static boolean isPasswordValid(Password candidate, PasswordPolicy policy) { ... }

Refactoring discipline (from Module 12): small verified steps, tests green between each, behavior unchanged by construction.