Modules cheatsheet

module_cheatsheet.rb

# Modules can be used for namespacing...

module Whizz
  class SoundEffect
    def noise
      "Whizzo!"
    end
  end

  class Popper
    def make_noise
      # Don't need to specify namespace when you are inside it.
      puts SoundEffect.new.noise
    end
  end
end

# Do need to specify namespace when you are outside it.
# Separate each level of spacing with ::
Whizz::Popper.new.make_noise


# And modules can be used to move shared functionality into one place.
module PowersOfArrest
  def can_arrest_people?
    true
  end
end

class PoliceOfficer
  # include makes all methods in the module instance methods on the class.
  include PowersOfArrest
  
  # This is like writing:
  #  def can_arrest_people?
  #    true
  #  end
end
puts PoliceOfficer.new.can_arrest_people?

class Robocop
  # extend makes all methods in the module class methods.
  extend PowersOfArrest
  
  # This is like writing:
  #  def self.can_arrest_people?
  #    true
  #  end
end
puts Robocop.can_arrest_people?