From 9f0a565c3d99b7f10fbcd2cf71d4f2f821551f28 Mon Sep 17 00:00:00 2001
From: Etienne Kneuss <colder@php.net>
Date: Wed, 31 Aug 2011 19:47:32 +0000
Subject: [PATCH] Draft for weakref documentation

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@315918 c90b9560-bf6c-de11-be94-00142212c4b1
---
 appendices/extensions.xml               |   2 +
 reference/weakref/book.xml              |  92 +++++++++++++
 reference/weakref/setup.xml             |  53 ++++++++
 reference/weakref/weakref.xml           | 120 +++++++++++++++++
 reference/weakref/weakref/acquire.xml   | 164 ++++++++++++++++++++++++
 reference/weakref/weakref/construct.xml | 113 ++++++++++++++++
 reference/weakref/weakref/get.xml       |  62 +++++++++
 reference/weakref/weakref/release.xml   | 108 ++++++++++++++++
 reference/weakref/weakref/test.php      |  33 +++++
 reference/weakref/weakref/valid.xml     |  63 +++++++++
 10 files changed, 810 insertions(+)
 create mode 100644 reference/weakref/book.xml
 create mode 100644 reference/weakref/setup.xml
 create mode 100644 reference/weakref/weakref.xml
 create mode 100644 reference/weakref/weakref/acquire.xml
 create mode 100644 reference/weakref/weakref/construct.xml
 create mode 100644 reference/weakref/weakref/get.xml
 create mode 100644 reference/weakref/weakref/release.xml
 create mode 100644 reference/weakref/weakref/test.php
 create mode 100644 reference/weakref/weakref/valid.xml

diff --git a/appendices/extensions.xml b/appendices/extensions.xml
index d43c4fe669..dfec4eab56 100644
--- a/appendices/extensions.xml
+++ b/appendices/extensions.xml
@@ -213,6 +213,7 @@
    <listitem><simpara><xref linkend="book.vpopmail"/></simpara></listitem>
    <listitem><simpara><xref linkend="book.w32api"/></simpara></listitem>
    <listitem><simpara><xref linkend="book.wddx"/></simpara></listitem>
+   <listitem><simpara><xref linkend="book.weakref"/></simpara></listitem>
    <listitem><simpara><xref linkend="book.win32ps"/></simpara></listitem>
    <listitem><simpara><xref linkend="book.win32service"/></simpara></listitem>
    <listitem><simpara><xref linkend="book.wincache"/></simpara></listitem>
@@ -561,6 +562,7 @@
     <listitem><para><xref linkend="book.tcpwrap"/></para></listitem>
     <listitem><para><xref linkend="book.vpopmail"/></para></listitem>
     <listitem><para><xref linkend="book.w32api"/></para></listitem>
+    <listitem><para><xref linkend="book.weakref"/></para></listitem>
     <listitem><para><xref linkend="book.win32ps"/></para></listitem>
     <listitem><para><xref linkend="book.win32service"/></para></listitem>
     <listitem><para><xref linkend="book.wincache"/></para></listitem>
diff --git a/reference/weakref/book.xml b/reference/weakref/book.xml
new file mode 100644
index 0000000000..85efda8c3c
--- /dev/null
+++ b/reference/weakref/book.xml
@@ -0,0 +1,92 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- $Revision: $ -->
+<!-- Membership: pecl -->
+
+<book xml:id="book.weakref" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
+ <title>Weak References</title>
+ <titleabbrev>Weakref</titleabbrev>
+ 
+ <preface xml:id="intro.weakref">
+  &reftitle.intro;
+  <para>
+   Weak references provide a non-intrusive gateway to ephemere objects. Unlike
+   normal (strong) references, weak references do not prevent the garbage
+   collector from freeing that object. For this reason, an object may be
+   destroyed even though a weak reference to that object still exists. In such
+   conditions, the weak reference seamlessly becomes invalid.
+   </para>
+
+   <para>
+    <example>
+     <title><classname>Weakref</classname> usage example</title>
+     <programlisting role="php">
+<![CDATA[
+<?php
+class MyClass {
+    public function __destruct() {
+        echo "Destroying object!\n";
+    }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+if ($r1->valid()) {
+    echo "Object still exists!\n";
+    var_dump($r1->get());
+} else {
+    echo "Object is dead!\n";
+}
+
+unset($o1);
+
+if ($r1->valid()) {
+    echo "Object still exists!\n";
+    var_dump($r1->get());
+} else {
+    echo "Object is dead!\n";
+}
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Object still exists!
+object(MyClass)#1 (0) {
+}
+Destroying object!
+Object is dead!
+]]>
+     </screen>
+    </example>
+   </para>
+ </preface>
+
+ &reference.weakref.setup;
+ &reference.weakref.weakref;
+
+</book>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
+
diff --git a/reference/weakref/setup.xml b/reference/weakref/setup.xml
new file mode 100644
index 0000000000..db67cc5285
--- /dev/null
+++ b/reference/weakref/setup.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- $Revision: $ -->
+
+<chapter xml:id="weakref.setup" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
+ &reftitle.setup;
+
+ <section xml:id="weakref.requirements">
+  &reftitle.required;
+  &no.requirement;
+ </section>
+
+ <section xml:id="weakref.installation">
+  &reftitle.install;
+  <para>
+   &pecl.moved;
+  </para>
+  <para>
+   &pecl.info;
+   <link xlink:href="&url.pecl.package;weakref">&url.pecl.package;weakref</link>.
+  </para>
+  <para>
+   &pecl.windows.download;
+  </para>
+ </section>
+
+ <section xml:id="weakref.resources">
+  &reftitle.resources;
+  &no.resource;
+ </section>
+
+</chapter>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
+
diff --git a/reference/weakref/weakref.xml b/reference/weakref/weakref.xml
new file mode 100644
index 0000000000..b7dcb437fe
--- /dev/null
+++ b/reference/weakref/weakref.xml
@@ -0,0 +1,120 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- $Revision: $ -->
+<phpdoc:classref xmlns:phpdoc="http://php.net/ns/phpdoc" xml:id="class.weakref" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude">
+ <title>The Weakref class</title>
+ <titleabbrev>Weakref</titleabbrev>
+
+ <partintro>
+
+<!-- {{{ weakref intro -->
+  <section xml:id="weakref.intro">
+   &reftitle.intro;
+   <para>
+    The Weakref class provides a gateway to objects without preventing the garbage collector from freeing those objects.
+    It also provides a way to turn a weak reference into a strong one.
+   </para>
+  </section>
+<!-- }}} -->
+
+  <section xml:id="weakref.synopsis">
+   &reftitle.classsynopsis;
+
+<!-- {{{ Synopsis -->
+   <classsynopsis>
+    <ooclass><classname>Weakref</classname></ooclass>
+
+<!-- {{{ Class synopsis -->
+
+    <classsynopsisinfo>
+     <ooclass>
+      <classname>Weakref</classname>
+     </ooclass>
+
+    </classsynopsisinfo>
+<!-- }}} -->
+
+    <classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
+    <xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.weakref')/db:refentry/db:refsect1[@role='description']/descendant::db:constructorsynopsis[1])" />
+    <xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.weakref')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[1])" />
+   </classsynopsis>
+
+  </section>
+<!-- {{{ weakref examples -->
+  <section xml:id="weakref.examples">
+   &reftitle.examples;
+   <para>
+    <example>
+     <title><classname>Weakref</classname> usage example</title>
+     <programlisting role="php">
+<![CDATA[
+<?php
+class MyClass {
+    public function __destruct() {
+        echo "Destroying object!\n";
+    }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+if ($r1->valid()) {
+    echo "Object still exists!\n";
+    var_dump($r1->get());
+} else {
+    echo "Object is dead!\n";
+}
+
+unset($o1);
+
+if ($r1->valid()) {
+    echo "Object still exists!\n";
+    var_dump($r1->get());
+} else {
+    echo "Object is dead!\n";
+}
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Object still exists!
+object(MyClass)#1 (0) {
+}
+Destroying object!
+Object is dead!
+]]>
+     </screen>
+    </example>
+   </para>
+  </section>
+<!-- }}} -->
+
+ </partintro>
+
+ &reference.weakref.entities.weakref;
+
+</phpdoc:classref>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
+
diff --git a/reference/weakref/weakref/acquire.xml b/reference/weakref/weakref/acquire.xml
new file mode 100644
index 0000000000..de2b92172f
--- /dev/null
+++ b/reference/weakref/weakref/acquire.xml
@@ -0,0 +1,164 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Revision: $ -->
+<refentry xml:id="weakref.acquire" xmlns="http://docbook.org/ns/docbook">
+ <refnamediv>
+  <refname>Weakref::acquire</refname>
+  <refpurpose>Aquires a strong reference on that object</refpurpose>
+ </refnamediv>
+
+ <refsect1 role="description">
+  &reftitle.description;
+  <methodsynopsis>
+   <modifier>public</modifier> <type>bool</type><methodname>Weakref::acquire</methodname>
+   <void/>
+  </methodsynopsis>
+  <para>
+    Acquires a strong reference on that object, virtually turning the weak
+    reference into a strong one.
+  </para>
+ </refsect1>
+
+ <refsect1 role="parameters">
+  &reftitle.parameters;
+  &no.function.parameters;
+ </refsect1>
+
+ <refsect1 role="returnvalues">
+  &reftitle.returnvalues;
+  <para>
+   Returns &true; if the reference was valid and could be turned into a strong
+   reference, &false; otherwise.
+  </para>
+ </refsect1>
+
+ <refsect1 role="examples">
+  &reftitle.examples;
+  <para>
+   <example>
+    <title><function>Weakref::acquire</function> example</title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+class MyClass {
+    public function __destruct() {
+        echo "Destroying object!\n";
+    }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+$r1->acquire();
+
+echo "Unsetting o1...\n";
+unset($o1);
+
+$o2 = $r1->get();
+
+$r1->release();
+
+echo "Unsetting o2...\n";
+unset($o2);
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Unsetting o1...
+Unsetting o2...
+Destroying object!
+]]>
+    </screen>
+   </example>
+  </para>
+
+  <para>
+   <example>
+    <title>Nested acquire/release example</title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+class MyClass {
+    public function __destruct() {
+        echo "Destroying object!\n";
+    }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+echo "Acquiring...\n";
+$r1->acquire();
+
+echo "  Unsetting...\n";
+unset($o1);
+
+echo "  Acquiring...\n";
+$r1->acquire();
+
+echo "    Acquiring...\n";
+$r1->acquire();
+
+echo "    Releasing...\n";
+$r1->release();
+
+echo "  Releasing...\n";
+$r1->release();
+
+echo "Releasing...\n";
+$r1->release();
+
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Acquiring...
+  Unsetting...
+  Acquiring...
+    Acquiring...
+    Releasing...
+  Releasing...
+Releasing...
+Destroying object!
+]]>
+    </screen>
+   </example>
+  </para>
+ </refsect1>
+
+ <refsect1 role="seealso">
+  &reftitle.seealso;
+  <para>
+   <simplelist>
+    <member><methodname>Weakref::release</methodname></member>
+   </simplelist>
+  </para>
+ </refsect1>
+
+</refentry>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
diff --git a/reference/weakref/weakref/construct.xml b/reference/weakref/weakref/construct.xml
new file mode 100644
index 0000000000..0ca91c08d4
--- /dev/null
+++ b/reference/weakref/weakref/construct.xml
@@ -0,0 +1,113 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Revision: $ -->
+<refentry xml:id="weakref.construct" xmlns="http://docbook.org/ns/docbook">
+ <refnamediv>
+  <refname>Weakref::__construct</refname>
+  <refpurpose>Constructs a new weak reference</refpurpose>
+ </refnamediv>
+
+ <refsect1 role="description">
+  &reftitle.description;
+  <constructorsynopsis>
+   <modifier>public</modifier> <methodname>Weakref::__construct</methodname>
+   <methodparam choice="opt"><type>object</type><parameter>object</parameter></methodparam>
+  </constructorsynopsis>
+  <para>
+   Constructs a new weak reference.
+  </para>
+ </refsect1>
+
+ <refsect1 role="parameters">
+  &reftitle.parameters;
+  <para>
+   <variablelist>
+    <varlistentry>
+     <term><parameter>object</parameter></term>
+     <listitem>
+      <para>
+        The object to reference.
+      </para>
+     </listitem>
+    </varlistentry>
+   </variablelist>
+  </para>
+ </refsect1>
+
+ <refsect1 role="returnvalues">
+  &reftitle.returnvalues;
+  <para>
+   &return.void;
+  </para>
+ </refsect1>
+
+ <refsect1 role="examples">
+  &reftitle.examples;
+  <para>
+   <example>
+    <title><function>Weakref::__construct</function> example</title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+class MyClass {
+    public function __destruct() {
+        echo "Destroying object!\n";
+    }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+if ($r1->valid()) {
+    echo "Object still exists!\n";
+    var_dump($r1->get());
+} else {
+    echo "Object is dead!\n";
+}
+
+unset($o1);
+
+if ($r1->valid()) {
+    echo "Object still exists!\n";
+    var_dump($r1->get());
+} else {
+    echo "Object is dead!\n";
+}
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Object still exists!
+object(MyClass)#1 (0) {
+}
+Destroying object!
+Object is dead!
+]]>
+    </screen>
+   </example>
+  </para>
+ </refsect1>
+</refentry>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
diff --git a/reference/weakref/weakref/get.xml b/reference/weakref/weakref/get.xml
new file mode 100644
index 0000000000..c8e37672cb
--- /dev/null
+++ b/reference/weakref/weakref/get.xml
@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Revision: $ -->
+<refentry xml:id="weakref.get" xmlns="http://docbook.org/ns/docbook">
+ <refnamediv>
+  <refname>Weakref::get</refname>
+  <refpurpose>Returns the object pointed to by the weak reference</refpurpose>
+ </refnamediv>
+
+ <refsect1 role="description">
+  &reftitle.description;
+  <methodsynopsis>
+   <modifier>public</modifier> <type>object</type><methodname>Weakref::get</methodname>
+   <void/>
+  </methodsynopsis>
+  <para>
+   Returns the object pointed to by the weak reference.
+  </para>
+ </refsect1>
+
+ <refsect1 role="parameters">
+  &reftitle.parameters;
+  &no.function.parameters;
+ </refsect1>
+
+ <refsect1 role="returnvalues">
+  &reftitle.returnvalues;
+  <para>
+   Returns the object if the reference is still valid, &null; otherwise.
+  </para>
+ </refsect1>
+
+ <refsect1 role="seealso">
+  &reftitle.seealso;
+  <para>
+   <simplelist>
+    <member><methodname>Weakref::valid</methodname></member>
+   </simplelist>
+  </para>
+ </refsect1>
+
+</refentry>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
diff --git a/reference/weakref/weakref/release.xml b/reference/weakref/weakref/release.xml
new file mode 100644
index 0000000000..9c496b956a
--- /dev/null
+++ b/reference/weakref/weakref/release.xml
@@ -0,0 +1,108 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Revision: $ -->
+<refentry xml:id="weakref.release" xmlns="http://docbook.org/ns/docbook">
+ <refnamediv>
+  <refname>Weakref::release</refname>
+  <refpurpose>Releases a previously acquired reference</refpurpose>
+ </refnamediv>
+
+ <refsect1 role="description">
+  &reftitle.description;
+  <methodsynopsis>
+   <modifier>public</modifier> <type>bool</type><methodname>Weakref::release</methodname>
+   <void/>
+  </methodsynopsis>
+  <para>
+    Releases a previously acquired reference. Potentially turning a strong
+    reference back into a weak reference.
+  </para>
+ </refsect1>
+
+ <refsect1 role="parameters">
+  &reftitle.parameters;
+  &no.function.parameters;
+ </refsect1>
+
+ <refsect1 role="returnvalues">
+  &reftitle.returnvalues;
+  <para>
+   Returns &true; if the reference was previously acquired and thus could be
+   released, &false; otherwise.
+  </para>
+ </refsect1>
+
+ <refsect1 role="examples">
+  &reftitle.examples;
+  <para>
+   <example>
+    <title><function>Weakref::release</function> example</title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+class MyClass {
+    public function __destruct() {
+        echo "Destroying object!\n";
+    }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+$r1->acquire();
+
+echo "Unsetting o1...\n";
+unset($o1);
+
+$o2 = $r1->get();
+
+$r1->release();
+
+echo "Unsetting o2...\n";
+unset($o2);
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Unsetting o1...
+Unsetting o2...
+Destroying object!
+]]>
+    </screen>
+   </example>
+  </para>
+ </refsect1>
+
+ <refsect1 role="seealso">
+  &reftitle.seealso;
+  <para>
+   <simplelist>
+    <member><methodname>Weakref::acquire</methodname></member>
+   </simplelist>
+  </para>
+ </refsect1>
+
+</refentry>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->
diff --git a/reference/weakref/weakref/test.php b/reference/weakref/weakref/test.php
new file mode 100644
index 0000000000..70f3fbea74
--- /dev/null
+++ b/reference/weakref/weakref/test.php
@@ -0,0 +1,33 @@
+<?php
+class MyClass {
+        public function __destruct() {
+                    echo "Destroying object!\n";
+                        }
+}
+
+$o1 = new MyClass;
+
+$r1 = new Weakref($o1);
+
+echo "Acquiring...\n";
+$r1->acquire();
+
+echo "  Unsetting...\n";
+unset($o1);
+
+echo "  Acquiring...\n";
+$r1->acquire();
+
+echo "    Acquiring...\n";
+$r1->acquire();
+
+echo "    Releasing...\n";
+$r1->release();
+
+echo "  Releasing...\n";
+$r1->release();
+
+echo "Releasing...\n";
+$r1->release();
+
+?>
diff --git a/reference/weakref/weakref/valid.xml b/reference/weakref/weakref/valid.xml
new file mode 100644
index 0000000000..8166de0263
--- /dev/null
+++ b/reference/weakref/weakref/valid.xml
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Revision: $ -->
+<refentry xml:id="weakref.valid" xmlns="http://docbook.org/ns/docbook">
+ <refnamediv>
+  <refname>Weakref::valid</refname>
+  <refpurpose>Checks whether the object referenced still exists</refpurpose>
+ </refnamediv>
+
+ <refsect1 role="description">
+  &reftitle.description;
+  <methodsynopsis>
+   <modifier>public</modifier> <type>bool</type><methodname>Weakref::valid</methodname>
+   <void/>
+  </methodsynopsis>
+  <para>
+   Checks whether the object referenced still exists.
+  </para>
+ </refsect1>
+
+ <refsect1 role="parameters">
+  &reftitle.parameters;
+  &no.function.parameters;
+ </refsect1>
+
+ <refsect1 role="returnvalues">
+  &reftitle.returnvalues;
+  <para>
+   Returns &true; if the object still exists and is thus still accessible via
+   <methodname>Weakref::get</methodname>, &false; otherwise.
+  </para>
+ </refsect1>
+
+ <refsect1 role="seealso">
+  &reftitle.seealso;
+  <para>
+   <simplelist>
+    <member><methodname>Weakref::get</methodname></member>
+   </simplelist>
+  </para>
+ </refsect1>
+
+</refentry>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->