Polymorphic Null Object

null_object.rb

class User
  def name
    'Mike Pack'
  end
end

class GuestUser
  def name
    'Guest User'
  end
end

class AdminUser
  def name
    'Admin User'
  end
end

class Controller
  def current_user
    return GuestUser.new if rand(0..1) == 0
    return AdminUser.new if rand(0..5) == 0

    User.new
  end

  def show
    puts current_user.name
  end
end

Controller.new.show