diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/core/disposable.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/core/disposable.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,132 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+module.metadata = {
+  "stability": "experimental"
+};
+
+
+const { Class } = require("./heritage");
+const { Observer, subscribe, unsubscribe, observe } = require("./observer");
+const { isWeak, WeakReference } = require("./reference");
+const method = require("../../method/core");
+
+const unloadSubject = require('@loader/unload');
+const addonUnloadTopic = "sdk:loader:destroy";
+
+
+
+const uninstall = method("disposable/uninstall");
+exports.uninstall = uninstall;
+
+
+const shutdown = method("disposable/shutdown");
+exports.shutdown = shutdown;
+
+const disable = method("disposable/disable");
+exports.disable = disable;
+
+const upgrade = method("disposable/upgrade");
+exports.upgrade = upgrade;
+
+const downgrade = method("disposable/downgrade");
+exports.downgrade = downgrade;
+
+const unload = method("disposable/unload");
+exports.unload = unload;
+
+const dispose = method("disposable/dispose");
+exports.dispose = dispose;
+dispose.define(Object, object => object.dispose());
+
+
+const setup = method("disposable/setup");
+exports.setup = setup;
+setup.define(Object, (object, ...args) => object.setup(...args));
+
+
+// Set's up disposable instance.
+const setupDisposable = disposable => {
+  subscribe(disposable, addonUnloadTopic, isWeak(disposable));
+};
+
+// Tears down disposable instance.
+const disposeDisposable = disposable => {
+  unsubscribe(disposable, addonUnloadTopic);
+};
+
+// Base type that takes care of disposing it's instances on add-on unload.
+// Also makes sure to remove unload listener if it's already being disposed.
+const Disposable = Class({
+  implements: [Observer],
+  initialize: function(...args) {
+    // First setup instance before initializing it's disposal. If instance
+    // fails to initialize then there is no instance to be disposed at the
+    // unload.
+    setup(this, ...args);
+    setupDisposable(this);
+  },
+  destroy: function(reason) {
+    // Destroying disposable removes unload handler so that attempt to dispose
+    // won't be made at unload & delegates to dispose.
+    disposeDisposable(this);
+    unload(this, reason);
+  },
+  setup: function() {
+    // Implement your initialize logic here.
+  },
+  dispose: function() {
+    // Implement your cleanup logic here.
+  }
+});
+exports.Disposable = Disposable;
+
+// Disposable instances observe add-on unload notifications in
+// order to trigger `unload` on them.
+observe.define(Disposable, (disposable, subject, topic, data) => {
+  const isUnloadTopic = topic === addonUnloadTopic;
+  const isUnloadSubject = subject.wrappedJSObject === unloadSubject;
+  if (isUnloadTopic && isUnloadSubject) {
+    unsubscribe(disposable, topic);
+    unload(disposable);
+  }
+});
+
+const unloaders = {
+  destroy: dispose,
+  uninstall: uninstall,
+  shutdown: shutdown,
+  disable: disable,
+  upgrade: upgrade,
+  downgrade: downgrade
+}
+const unloaded = new WeakMap();
+unload.define(Disposable, (disposable, reason) => {
+  if (!unloaded.get(disposable)) {
+    unloaded.set(disposable, true);
+    // Pick an unload handler associated with an unload
+    // reason (falling back to destroy if not found) and
+    // delegate unloading to it.
+    const unload = unloaders[reason] || unloaders.destroy;
+    unload(disposable);
+  }
+});
+
+
+// If add-on is disabled munally, it's being upgraded, downgraded
+// or uniststalled `dispose` is invoked to undo any changes that
+// has being done by it in this session.
+disable.define(Disposable, dispose);
+downgrade.define(Disposable, dispose);
+upgrade.define(Disposable, dispose);
+uninstall.define(Disposable, dispose);
+
+// If application is shut down no dispose is invoked as undo-ing
+// changes made by instance is likely to just waste of resources &
+// increase shutdown time. Although specefic components may choose
+// to implement shutdown handler that does something better.
+shutdown.define(Disposable, disposable => {});
+