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diff pseudo-weak-refs/index.html @ 18:08bddf757ed8

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Added pseudo-weak-refs feed.
author Atul Varma <varmaa@toolness.com>
date Sat, 25 Apr 2009 13:38:25 -0700
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pseudo-weak-refs/index.html	Sat Apr 25 13:38:25 2009 -0700
@@ -0,0 +1,80 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
+          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+<head>
+  <meta http-equiv="Content-type" content="text/html; charset=utf-8" />
+  <link rel="stylesheet" type="text/css" media="all"
+        href="index.css" />
+  <link rel="commands" href="pseudo-weak-refs.js"/>
+  <title>Pseudo Weak References for Web Content</title>
+</head>
+<body>
+<div id="container">
+<div id="content">
+<h1>Pseudo Weak References for Web Content</h1>
+<p>This Ubiquity feed provides pseudo weak reference functionality to
+web content, for the purpose of making it easier to debug memory
+management issues. Specifically, it adds two new functions to 
+the global <tt>window</tt> object of all web pages:</p>
+<ul>
+  <li><tt>PseudoWeakRef(object)</tt> is a constructor that makes a
+    pseudo-weak reference for the object.  The returned object has one
+    method, <tt>exists()</tt>, which returns whether or not the
+    referent still exists.</li>
+  <li><tt>forceGC()</tt> forces garbage collection.</li>
+</ul>
+<p>Here's some example code:</p>
+<script id="tests">
+function testExistsReturnsFalse() {
+  var object = new Object();
+  var weak = new PseudoWeakRef(object);
+
+  // Destroy our one strong reference to the object, leaving it available
+  // for garbage collection.
+  object = null;
+
+  forceGC();
+  if (weak.exists())
+    throw new Error("weak referent should not exist");
+}
+</script>
+<p>The above source code is actually part of the test suite for this
+feed.  <span id="test-result">If this feed were installed, the suite would
+run now.</span></p>
+<p>The source code for this feed can be viewed
+at <a href="pseudo-weak-refs.js">pseudo-weak-refs.js</a>.</p>
+</div>
+<div id="messages">
+<span id="tests-failed">The suite was run, but some tests failed.</span>
+<span id="tests-passed">The suite was run, and all tests passed.</span>
+</div>
+</div>
+<script>
+function testExistsReturnsTrue() {
+  var object = new Object();
+  var weak = new PseudoWeakRef(object);
+  forceGC();
+  if (!weak.exists())
+    throw new Error("weak referent should exist");
+}
+
+function onLoad() {
+  function $(id) { return document.getElementById(id); }
+
+  $("tests").innerHTML = $("tests").innerHTML.slice(1);
+  if (window.PseudoWeakRef && window.forceGC) {
+    try {
+      testExistsReturnsFalse();
+      testExistsReturnsTrue();
+    } catch (e) {
+      $("test-result").innerHTML = $("tests-failed").innerHTML;
+      throw e;
+    }
+    $("test-result").innerHTML = $("tests-passed").innerHTML;
+  }
+}
+
+window.addEventListener("load", onLoad, false);
+</script>
+</body>
+</html>