service_objects_bp_5.rb

class CommentCreator
  #...

  def perform
    ThreadParticipantsNotifier.new(@comment).notify
    CommentReplyNotifier.new(@comment).notify
    Kissmetrics.record(comment.author, 'Added Comment')
  end
end

class CommentReplyNotifier
  def initialize(comment)
    @comment = comment
  end

  def notify
    if previous_comment?
      ReplyMailer.notification(in_reply_to_user, @comment).deliver
    end
  end

  private

  def previous_comment?
    !!previous_comment
  end

  def previous_comment
    @comment.previous_comment
  end

  def in_reply_to_user
    previous_comment.author
  end
end