[Ruby] Modules -- Ex

Namespacing

Create a module named GameUtils and place the lend_to_friend method inside the module. Changelend_to_friend to a class method by prefixing it with self..
You won't need to require this module since it'll be inside the same file (already required), but you will have to namespace your method call.

class Game
  def initialize(name)
    @name = name
  end
end

Answer:

module GameUtils
  def self.lend_to_friend(game, friend_email)
    end
end

game = Game.new("Contra")
GameUtils.lend_to_friend(game, "gregg@codeschool.com") 

 

Mixin

Re-open the Game class and include theGameUtils module so its methods are exposed as instance methods. Make sure to do this before it is called.

Answer:

class Game
  include GameUtils
end
game = Game.new("contra")
game.lend_to_friend("Gregg")

 

Extend

Good job! Now expose the methods from the GameUtils module as class methods of the Game class.

class Game
  extend GameUtils
end

Game.find_all_from_user("Gregg")

 

Object Extend

Extend the single game object with the Playable module, so we can call the play method on it.

game = Game.new("Contra")
game.extend(Playable)
game.play

 

Hook Methods

Define a new self.included method hook for the LibraryUtils module which will extend the ClassMethods on the passed in class. Also, since we'll now be extending ClassMethods when LibraryUtils is included, remove duplicate code in the AtariLibrary class.

module LibraryUtils
  
  def add_game(game)
  end

  def remove_game(game)
  end

  module ClassMethods
    def search_by_game_name(name)
    end
  end
end

class AtariLibrary
  include LibraryUtils
  extend LibraryUtils::ClassMethods
end

Answer:

module LibraryUtils

  def self.included(base)
    base.extend(ClassMethods)
  end
  
  def add_game(game)
  end

  def remove_game(game)
  end

  module ClassMethods
    def search_by_game_name(name)
    end
  end
end

class AtariLibrary
  include LibraryUtils
end

 

ActiveSupport::Concern - Part I

Now refactor the following code to use ActiveSupport::Concern's ability to expose class methods from a module.

module LibraryUtils

  def self.included(base)
    base.extend(ClassMethods)
  end

  def add_game(game)
  end

  def remove_game(game)
  end

  module ClassMethods
    def search_by_game_name(name)
    end
  end
end

Answer: ActiveSupport::Concern can replace self.included

module LibraryUtils
  extend ActiveSupport::Concern
  
  def add_game(game)
  end

  def remove_game(game)
  end

  module ClassMethods
    def search_by_game_name(name)
    end
  end
end

 

ActiveSupport::Concern - Part II

Call the included method from inside the LibraryUtils module and pass in a block that calls theload_game_list class method.

module LibraryUtils

  extend ActiveSupport::Concern
  included do
    load_game_list 
  end
  
  def add_game(game)
  end

  def remove_game(game)
  end

  module ClassMethods
    def search_by_game_name(name)
    end

    def load_game_list
    end
  end
end

 

ActiveSupport::Concern - Part III

Make sure the AtariLibrary class includes only the LibraryUtils module and let ActiveSupport::Concern take care of loading its dependencies. Then, refactor the self.included method on LibraryUtils to use theincluded method.

module LibraryLoader

  extend ActiveSupport::Concern

  module ClassMethods
    def load_game_list
    end
  end
end

module LibraryUtils
  def self.included(base)
    base.load_game_list
  end
end

class AtariLibrary
  include LibraryLoader
  include LibraryUtils
end

Answer:

module LibraryLoader

  extend ActiveSupport::Concern

  module ClassMethods
    def load_game_list
    end
  end
end

module LibraryUtils
  extend ActiveSupport::Concern
  include LibraryLoader
  included do
    load_game_list
  end
end

class AtariLibrary
  include LibraryUtils
end