title: Moodle - extending an existing plugin
body: <p>I would like to add a functionality to the existing forum plugin. The functionality I want is that I can select a <strong>published date</strong> when creating a post in a forum. When I select a date a week in the future, the post will be published (and shown to the user) a week in the future.</p>
  
  <p>I think the following need to happen:</p>
  
  <ul>
  <li>Add a <strong>published_date</strong> field to table <strong>mdl_forum_posts</strong> </li>
  <li>Change query that shows the posts in the forum (select posts where published date is in the past) </li>
  <li>Change cron that sends notifications of forum posts (that
  only published posts will be sent)</li>
  </ul>
  
  <p>Now I'm wondering if there's already a plugin that provides this functionality. I've searched in plugins but couldn't find any with this functionality. </p>
  
  <p>And how can I code this functionality? I don't think it's good to overwrite the core code of the plugin. How can I extend this plugin with clean structure/code? </p>
  
  <p>Can you help me on my way?</p>