title: MVP Pattern: should multiple Presenters be decoupled or can they communicate directly?
body: <p>I have a ui that looks like this:</p>
  
  <pre><code>    +--------+---------------+
      | model1 | model details |
      | model2 |     here,     |
      | model3 | loaded as the |
      |        | user selects  |
      |        | a model from  |
      |        |   the left.   |
      |        |               |
      +--------+---------------+
  </code></pre>
  
  <p>I'm using the <a href="https://stackoverflow.com/questions/2056/what-are-mvp-and-mvc-and-what-is-the-difference/101561#101561">MVP pattern</a> to drive this ui.</p>
  
  <p>I'm simplifying a lot here, but in order to divide and conquer I would like to split the Presenter into two: one that handles user gestures in the View on the left (the user changes the Model list in this View, eg sorting) and another Presenter that handles user gestures in the View on the right (the user changes the individual model in this View).</p>
  
  <p>While the Presenter on the left interacts with the entire list of Models, the Presenter on the right interacts with only a single Model: the one the user selects from the list on the left. IOW the ui is driven from left to right.</p>
  
  <p>After the user chooses (ie, clicks) a model on the left, my current implementation looks like (roughly):</p>
  
  <pre><code>LeftPresenter.onModelClick = function(event) {
      var model = this.getModelFromEvent(event);
      this.view.setSelectedModel(model); // updates list widget on left
      RightPresenter.setSelectedModel(model); // notify the other Presenter
  }
  
  RightPresenter.setSelectedModel = function(model) {
      // lazy load the model from the db, and update the
      // view when the model fires the "loadComplete" event
      model.bind('loadComplete', this.view.setModel);
      model.lazyLoad();
  }
  </code></pre>
  
  <p>Here is the part I am fuzzy on wrt the MVP pattern, or any MVC GUI pattern for that matter:</p>
  
  <ol>
  <li>Can a ui be driven by multiple Presenters like this?</li>
  <li>Should multiple Presenters be decoupled or can they communicate directly with each other as shown here?</li>
  </ol>
  
  <p>So my question boils down to: <strong>what's the best way to indicate to <code>RightPresenter</code> that the user selected a model in <code>LeftPresenter</code>'s view</strong>?</p>