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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<reference xml:id="class.weakreference" role="class" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude">
<title>The WeakReference class</title>
<titleabbrev>WeakReference</titleabbrev>
<partintro>
<!-- {{{ WeakReference intro -->
<section xml:id="weakreference.intro">
&reftitle.intro;
<para>
Weak references allow the programmer to retain a reference to an object which does not prevent
the object from being destroyed. They are useful for implementing cache like structures.
If the original object has been destroyed, &null; will be returned
when calling the <methodname>WeakReference::get</methodname> method.
The original object will be destroyed when the
<link linkend="features.gc.refcounting-basics">refcount</link> for it drops to zero;
creating weak references does not increase the <literal>refcount</literal> of the object being referenced.
</para>
<para>
<classname>WeakReference</classname>s cannot be serialized.
</para>
</section>
<!-- }}} -->
<section xml:id="weakreference.synopsis">
&reftitle.classsynopsis;
<!-- {{{ Synopsis -->
<classsynopsis class="class">
<ooclass>
<modifier>final</modifier>
<classname>WeakReference</classname>
</ooclass>
<classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.weakreference')/db:refentry/db:refsect1[@role='description']/descendant::db:constructorsynopsis[@role='WeakReference'])">
<xi:fallback/>
</xi:include>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.weakreference')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[@role='WeakReference'])">
<xi:fallback/>
</xi:include>
</classsynopsis>
<!-- }}} -->
</section>
<section xml:id="weakreference.examples">
<title>WeakReference Examples</title>
<para>
<example xml:id="weakreference.basic-example">
<title>Basic WeakReference Usage</title>
<programlisting role="php">
<![CDATA[
<?php
$obj = new stdClass();
$weakref = WeakReference::create($obj);
var_dump($weakref->get());
unset($obj);
var_dump($weakref->get());
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
object(stdClass)#1 (0) {
}
NULL
]]>
</screen>
</example>
</para>
</section>
</partintro>
&language.predefined.weakreference.construct;
&language.predefined.weakreference.create;
&language.predefined.weakreference.get;
</reference>
<!-- Keep this comment at the end of the file
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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
-->
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