Example of ghost loading pattern

episode.rb

class Episode
  def self.lazy_accessor(*names)
    names.each do |name|
      attr_writer name
      define_method(name) do
        load
        instance_variable_get("@#{name}")
      end
    end
  end

  attr_accessor :video,
                :id,
                :number,
                :name,
                :video_url,
                :load_state,
                :data_source


  # below is a macro which uses meta programming
  lazy_accessor :description,
                :synopsis,
                :publish_time

  def initialize(attributes={})
    attributes.each do |key, value|
      public_send("#{key}=", value)
    end
    
    @load_state = :ghost
  end

  def to_s
    inspect
  end

  def ==(other)
    other.is_a?(Episode) && other.id == id
  end

  def published?(time_now=Time.now)
    publish_time <= time_now
  end

  def load
    return if load_state == :loaded
    data_source.load(self)
  end
end