Dead Code

Unused variables, parameters, methods, files.

Fowler & Beck

Signs of Use (Symptoms)

  • Unreachable code after a return or throw.
  • Functions/classes that are never called.
  • Commented-out code blocks left “just in case”.

Why it is bad (Consequences)

  • Clutter: Distracts readers.
  • Confusion: Is this code important? Is it a bug that it’s not called?

Why it happens (Root Cause)

Code was deleted logically (no callers) but not physically. Fear of “needing it later”.

When it might be okay (Exceptions)

  • Debugging code temporarily disabled.
  • Feature flags (code is conditionally live).

Explanation

Problem

oldCalculation() was replaced by newCalculation(). oldCalculation() still exists.

The Flaw

No one will ever call oldCalculation(). It’s cruft. Delete it.

Real world analogy

Keeping expired milk in the fridge “just in case”.

Refactoring Solution

  • Delete it. Version control (Git) remembers if you need it.

Pros and Cons (of the Antipattern)

Pros (Why people do it) Cons (The price you pay)
  • “Might need it later”
    		•
  • Clutter
  • Confusion
    		•

    Comparison

    • Related Antipatterns: Speculative Generality.
    • Related Principles: YAGNI.

    Code example

    Typescript

    Bad (The Antipattern)

    Good (The Fix)