include_vs_extend

🔄 Include vs Extend

Understanding when to use include versus extend helps you organize shared behavior in classes and modules. include mixes module methods as instance methods, while extend adds them as class methods. Use extend for utility methods scoped to the class and include for behaviors each instance needs.

module Loggable
  def log(message)
    puts "[LOG] #{message}"
  end
end

class ServiceA
  include Loggable   # service_a.log(...) available on instances
end

class ServiceB
  extend Loggable    # ServiceB.log(...) available on class
end