# Decorators let you layer on functionality to existing operations, i.e serve a similar purpose to callbacks.
# For cases where including callback logic in the model would give the model too many responsibilities, a Decorator is useful.

# Imagine we have this logic on stackoverflow:
# A user can post a question on a stackoverflow, after posting an email notification is sent to
# all users have interest in the question topic, a post is shared on the user profile with a link to the question he posted

# BAD
# app/models/question.rb
after_create :handle_after_create_logic
private
  def handle_after_create_logic
    # queue email to be sent
    # create post
  end
# The question model should not be responsible for all this logic

# Good
class SOFQuestionNotifier
  def initialize(question)
    @question = question
  end

  def save
    if @question.save
      post_to_wall
      queue_emails
    end
  end 

private

  def post_to_wall
  end
  def queue_emails
  end
end

# app/controllers/questions_controller
def create
  @question = SOFQuestionNotifier.new(Question.new(params[:question]))
  if @question.save
    # Success
  else
    # Error
  end
end