diff -r 000000000000 -r 6474c204b198 addon-sdk/source/lib/sdk/ui/id.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/lib/sdk/ui/id.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+/* 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 method = require('../../method/core');
+const { uuid } = require('../util/uuid');
+
+// NOTE: use lang/functional memoize when it is updated to use WeakMap
+function memoize(f) {
+  const memo = new WeakMap();
+
+  return function memoizer(o) {
+    let key = o;
+    if (!memo.has(key))
+      memo.set(key, f.apply(this, arguments));
+    return memo.get(key);
+  };
+}
+
+let identify = method('identify');
+identify.define(Object, memoize(function() { return uuid(); }));
+exports.identify = identify;