dead-code.md

Dead Code

Dead Code is code that has no effect. It can be removed without impacting the behavior of the system.

What It Looks Like

Dead code takes many forms.

A condition that's always false:

items = []
if items.any?
  do_something
end

A condition that's always true:

message = "hello"
unless message.nil?
  puts message
end

A variable that's unused:

def average(a, b)
  sum = a + b
  (a + b) / 2.0
end

A method that's never called:

def foo
  false
end

Dead code is easiest to spot when it's a whole line or multiple lines, but sometimes a single subexpression can be dead. For example:

if transactions.empty? || transactions.all?(&:complete?)
  # ...
end

Here, the empty? check is not needed, because all? returns true when the collection is empty.

Why It Hurts

Code that's not needed is waste. Imagine painstakingly trying to understand some code, or perhaps even refactoring it, and then finding out that it's not used!

How To Fix It

Use Remove Dead Code.