Add Discourse.Singleton class mixin for creating singletons.

app/assets/javascripts/discourse/components/screen_track.js

@@ -98,7 +98,7 @@ Discourse.ScreenTrack = Ember.Object.extend({
       highestSeen = Math.max(highestSeen, parseInt(postNumber, 10));
     });
 
-    var highestSeenByTopic = Discourse.Session.current('highestSeenByTopic');
+    var highestSeenByTopic = Discourse.Session.currentProp('highestSeenByTopic');
     if ((highestSeenByTopic[topicId] || 0) < highestSeen) {
       highestSeenByTopic[topicId] = highestSeen;
       Discourse.TopicTrackingState.current().updateSeen(topicId, highestSeen);

app/assets/javascripts/discourse/mixins/singleton.js

@@ -0,0 +1,45 @@
+/**
+  This mixin allows a class to return a singleton, as well as a method to quickly
+  read/write attributes on the singleton.
+
+  @class Discourse.Singleton
+  @extends Ember.Mixin
+  @namespace Discourse
+  @module Discourse
+**/
+Discourse.Singleton = Em.Mixin.create({
+
+  /**
+    Returns the current singleton instance of the class.
+
+    @method current
+    @returns {Ember.Object} the instance of the singleton
+  **/
+  current: function() {
+    if (!this._current) {
+      this._current = this.create({});
+    }
+
+    return this._current;
+  },
+
+  /**
+    Returns or sets a property on the singleton instance.
+
+    @method currentProp
+    @param {String} property the property we want to get or set
+    @param {String} value the optional value to set the property to
+    @returns the value of the property
+  **/
+  currentProp: function(property, value) {
+    if (typeof(value) !== "undefined") {
+      this.current().set(property, value);
+      return value;
+    } else {
+      return this.current().get(property);
+    }
+  }
+
+});
+
+

app/assets/javascripts/discourse/models/session.js

@@ -1,6 +1,6 @@
 /**
   A data model representing current session data. You can put transient
-  data here you might want later.
+  data here you might want later. It is not stored or serialized anywhere.
 
   @class Session
   @extends Discourse.Model
@@ -13,28 +13,4 @@ Discourse.Session = Discourse.Model.extend({
   }
 });
 
-Discourse.Session.reopenClass({
-
-  /**
-    Returns the current session.
-
-    @method current
-    @returns {Discourse.Session} the current session singleton
-  **/
-  current: function(property, value) {
-    if (!this.currentSession) {
-      this.currentSession = Discourse.Session.create();
-    }
-
-    // If we found the current session
-    if (typeof property !== "undefined") {
-      if (typeof value !== "undefined") {
-        this.currentSession.set(property, value);
-      } else {
-        return this.currentSession.get(property);
-      }
-    }
-
-    return property ? this.currentSession.get(property) : this.currentSession;
-  }
-});
+Discourse.Session.reopenClass(Discourse.Singleton);

app/assets/javascripts/discourse/models/topic.js

@@ -87,7 +87,7 @@ Discourse.Topic = Discourse.Model.extend({
   // So take what the browser has seen into consideration.
   displayNewPosts: function() {
     var delta, highestSeen, result;
-    if (highestSeen = Discourse.Session.current('highestSeenByTopic')[this.get('id')]) {
+    if (highestSeen = Discourse.Session.currentProp('highestSeenByTopic')[this.get('id')]) {
       delta = highestSeen - this.get('last_read_post_number');
       if (delta > 0) {
         result = this.get('new_posts') - delta;

app/assets/javascripts/discourse/models/topic_list.js

@@ -45,7 +45,7 @@ Discourse.TopicList = Discourse.Model.extend({
           });
 
           topicList.set('more_topics_url', result.topic_list.more_topics_url);
-          Discourse.Session.current('topicList', topicList);
+          Discourse.Session.currentProp('topicList', topicList);
           topicList.set('loadingMore', false);
 
           return result.topic_list.more_topics_url;
@@ -75,7 +75,7 @@ Discourse.TopicList = Discourse.Model.extend({
           t.set('highlight', true);
           topics.insertAt(0,t);
         });
-        Discourse.Session.current('topicList', topicList);
+        Discourse.Session.currentProp('topicList', topicList);
       });
   }
 });

app/assets/javascripts/discourse/routes/filtered_list_route.js

@@ -41,7 +41,7 @@ Discourse.FilteredListRoute = Discourse.Route.extend({
       listController.set('canCreateTopic', topicList.get('can_create_topic'));
       listTopicsController.set('model', topicList);
 
-      var scrollPos = Discourse.Session.current('topicListScrollPosition');
+      var scrollPos = Discourse.Session.currentProp('topicListScrollPosition');
       if (scrollPos) {
         Em.run.next(function() {
           $('html, body').scrollTop(scrollPos);

app/assets/javascripts/discourse/routes/topic_route.js

@@ -71,7 +71,7 @@ Discourse.TopicRoute = Discourse.Route.extend({
     this._super();
 
     var topic = this.modelFor('topic');
-    Discourse.Session.current('lastTopicIdViewed', parseInt(topic.get('id'), 10));
+    Discourse.Session.currentProp('lastTopicIdViewed', parseInt(topic.get('id'), 10));
     this.controllerFor('search').set('searchContext', topic.get('searchContext'));
   },
 

app/mailers/user_notifications.rb

@@ -100,7 +100,6 @@ class UserNotifications < ActionMailer::Base
   end
 
   def notification_email(user, opts)
-
     return unless @notification = opts[:notification]
     return unless @post = opts[:post]
 

test/javascripts/mixins/singleton_test.js

@@ -0,0 +1,37 @@
+module("Discourse.Singleton");
+
+test("current", function() {
+  var DummyModel = Ember.Object.extend({});
+  DummyModel.reopenClass(Discourse.Singleton);
+
+  var current = DummyModel.current();
+  present(current, 'current returns the current instance');
+  equal(current, DummyModel.current(), 'calling it again returns the same instance');
+  notEqual(current, DummyModel.create({}), 'we can create other instances that are not the same as current');
+});
+
+test("currentProp reading", function() {
+  var DummyModel = Ember.Object.extend({});
+  DummyModel.reopenClass(Discourse.Singleton);
+  var current = DummyModel.current();
+
+  blank(DummyModel.currentProp('evil'), 'by default attributes are blank');
+  current.set('evil', 'trout');
+  equal(DummyModel.currentProp('evil'), 'trout', 'after changing the instance, the value is set');
+});
+
+test("currentProp writing", function() {
+  var DummyModel = Ember.Object.extend({});
+  DummyModel.reopenClass(Discourse.Singleton);
+
+  blank(DummyModel.currentProp('adventure'), 'by default attributes are blank');
+  var result = DummyModel.currentProp('adventure', 'time');
+  equal(result, 'time', 'it returns the new value');
+  equal(DummyModel.currentProp('adventure'), 'time', 'after calling currentProp the value is set');
+
+  DummyModel.currentProp('count', 0);
+  equal(DummyModel.currentProp('count'), 0, 'we can set the value to 0');
+
+  DummyModel.currentProp('adventure', null);
+  equal(DummyModel.currentProp('adventure'), null, 'we can set the value to null');
+});

test/javascripts/models/session_test.js

@@ -1,25 +1,6 @@
 module("Discourse.Session");
 
-test('current', function(){
-  var session = Discourse.Session.current();
-
-  present(session, "We have a current site session");
-  equal(session, Discourse.Session.current(), "Calling it a second time returns the same instance");
-
-  blank(Discourse.Session.current('orange'), "by default properties are nil");
-  session.set('orange', 'newBlack');
-  equal(Discourse.Session.current('orange'), "newBlack", "it remembers values");
-
-  Discourse.Session.current('orange', 'juice');
-  equal(session.get('orange'), "juice", "it can be updated");
-
-  Discourse.Session.current('zero', 0);
-  equal(session.get('zero'), 0);
-});
-
 test('highestSeenByTopic', function() {
-
   var session = Discourse.Session.current();
   deepEqual(session.get('highestSeenByTopic'), {}, "by default it returns an empty object");
-
 });