Repeated Switches

Apply refactorings

Replace Conditional with Polymorphism

Referenced by patterns

HumanAgent

Symptom

The agent finds the same switch (or if/else chain) over a type code in multiple files; adding a new case requires the agent to grep for every site and update each consistently.

Goal

Each case is a class implementing a shared interface; the agent adds a new case by adding one class, and the type checker tells it what's still missing.

Smellier version

switch (event.kind) {
  case 'click': return onClick(event);
  case 'key':   return onKey(event);
  case 'drag':  return onDrag(event);
}

Fresher version

event.handle(); // ClickEvent, KeyEvent, DragEvent each implement handle()

Example source: Illustrative example written for this site, not a quotation from any source.

Pressure

Dispatch logic duplicates across files; new cases are easy to miss; chained edits across all switch sites compound the agent's review burden per change.

Tradeoff

Polymorphic dispatch is implicit at call sites — the agent can no longer see the full set of branches in one place and must enumerate subclasses across files to reason about behavior.

Relief

Adding a new variant is mechanical and the type checker enforces completeness; the agent's plan-and-execute loop for new cases is bounded.

Trap

Replacing every switch with polymorphism, even ones with two stable cases, creates a class hierarchy the agent must navigate without buying any extension flexibility.