Use an `itemController` for topic lists. This will make bulk operations

easier.

app/assets/javascripts/discourse/controllers/discovery_topics_controller.js

@@ -8,10 +8,6 @@
 **/
 Discourse.DiscoveryTopicsController = Discourse.DiscoveryController.extend({
   actions: {
-    // Star a topic
-    toggleStar: function(topic) {
-      topic.toggleStar();
-    },
 
     // Show newly inserted topics
     showInserted: function() {

app/assets/javascripts/discourse/controllers/topic_list_item_controller.js

@@ -0,0 +1,21 @@
+/**
+  Handles displaying of a topic as a list item
+
+  @class TopicListItemController
+  @extends Discourse.ObjectController
+  @namespace Discourse
+  @module Discourse
+**/
+Discourse.TopicListItemController = Ember.ObjectController.extend({
+  needs: ['discoveryTopics'],
+
+  canStar: Em.computed.alias('controllers.discoveryTopics.currentUser.id'),
+  hideCategory: Em.computed.alias('controllers.discoveryTopics.hideCategory'),
+
+  actions: {
+    toggleStar: function() {
+      this.get('model').toggleStar();
+    }
+  }
+});
+

app/assets/javascripts/discourse/templates/discovery/topics.js.handlebars

@@ -45,7 +45,7 @@
         </tbody>
       {{/if}}
 
-      {{collection contentBinding="topics" tagName="tbody" itemViewClass="Discourse.TopicListItemView"}}
+      {{each topics itemController="topicListItem" itemViewClass="Discourse.TopicListItemView"}}
     </table>
   {{/if}}
 </div>

app/assets/javascripts/discourse/templates/list/topic_list_item.js.handlebars

@@ -1,6 +1,6 @@
-{{#if controller.currentUser.id}}
+{{#if canStar}}
   <td class='star'>
-    <a {{bind-attr class=":star :fa :fa-star starred:starred"}} {{action toggleStar this}} href='#' {{bind-attr title="starTooltip"}}></a>
+    <a {{bind-attr class=":star :fa :fa-star starred:starred"}} {{action toggleStar}} href='#' {{bind-attr title="starTooltip"}}></a>
   </td>
 {{/if}}
 
@@ -30,10 +30,8 @@
   {{/if}}
 </td>
 
-{{#unless controller.hideCategory}}
-<td class='category'>
-  {{categoryLink category}}
-</td>
+{{#unless hideCategory}}
+<td class='category'>{{categoryLink category}}</td>
 {{/unless}}
 
 <td class='posters'>