diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/util/registry.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/util/registry.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,59 @@
+/* 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": "unstable"
+};
+
+const { EventEmitter } = require('../deprecated/events');
+const unload = require('../system/unload');
+
+const Registry = EventEmitter.compose({
+  _registry: null,
+  _constructor: null,
+  constructor: function Registry(constructor) {
+    this._registry = [];
+    this._constructor = constructor;
+    this.on('error', this._onError = this._onError.bind(this));
+    unload.ensure(this, "_destructor");
+  },
+  _destructor: function _destructor() {
+    let _registry = this._registry.slice(0);
+    for each (let instance in _registry)
+      this._emit('remove', instance);
+    this._registry.splice(0);
+  },
+  _onError: function _onError(e) {
+    if (!this._listeners('error').length)
+      console.error(e);
+  },
+  has: function has(instance) {
+    let _registry = this._registry;
+    return (
+      (0 <= _registry.indexOf(instance)) ||
+      (instance && instance._public && 0 <= _registry.indexOf(instance._public))
+    );
+  },
+  add: function add(instance) {
+    let { _constructor, _registry } = this; 
+    if (!(instance instanceof _constructor))
+      instance = new _constructor(instance);
+    if (0 > _registry.indexOf(instance)) {
+      _registry.push(instance);
+      this._emit('add', instance);
+    }
+    return instance;
+  },
+  remove: function remove(instance) {
+    let _registry = this._registry;
+    let index = _registry.indexOf(instance)
+    if (0 <= index) {
+      this._emit('remove', instance);
+      _registry.splice(index, 1);
+    }
+  }
+});
+exports.Registry = Registry;
+