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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<reference xml:id="class.weakmap" 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 WeakMap class</title>
<titleabbrev>WeakMap</titleabbrev>
<partintro>
<!-- {{{ WeakMap intro -->
<section xml:id="weakmap.intro">
&reftitle.intro;
<para>
A <classname>WeakMap</classname> is map (or dictionary) that accepts objects as keys. However, unlike the
otherwise similar <classname>SplObjectStorage</classname>, an object in a key of <classname>WeakMap</classname>
does not contribute toward the object's reference count. That is, if at any point the only remaining reference
to an object is the key of a <classname>WeakMap</classname>, the object will be garbage collected and removed
from the <classname>WeakMap</classname>. Its primary use case is for building caches of data derived from
an object that do not need to live longer than the object.
</para>
<para>
<classname>WeakMap</classname> implements <interfacename>ArrayAccess</interfacename>,
<interfacename>Traversable</interfacename> (via <interfacename>IteratorAggregate</interfacename>),
and <interfacename>Countable</interfacename>, so in most cases it can be used in the same fashion as an associative array.
</para>
</section>
<!-- }}} -->
<section xml:id="weakmap.synopsis">
&reftitle.classsynopsis;
<!-- {{{ Synopsis -->
<classsynopsis class="class">
<ooclass>
<modifier>final</modifier>
<classname>WeakMap</classname>
</ooclass>
<oointerface>
<modifier>implements</modifier>
<interfacename>ArrayAccess</interfacename>
</oointerface>
<oointerface>
<interfacename>Countable</interfacename>
</oointerface>
<oointerface>
<interfacename>IteratorAggregate</interfacename>
</oointerface>
<classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.weakmap')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[@role='WeakMap'])">
<xi:fallback/>
</xi:include>
</classsynopsis>
<!-- }}} -->
</section>
<!-- {{{ weakmap examples -->
<section xml:id="weakmap.examples">
&reftitle.examples;
<para>
<example>
<title><classname>Weakmap</classname> usage example</title>
<programlisting role="php">
<![CDATA[
<?php
$wm = new WeakMap();
$o = new stdClass;
class A {
public function __destruct() {
echo "Dead!\n";
}
}
$wm[$o] = new A;
var_dump(count($wm));
echo "Unsetting...\n";
unset($o);
echo "Done\n";
var_dump(count($wm));
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
int(1)
Unsetting...
Dead!
Done
int(0)
]]>
</screen>
</example>
</para>
</section>
<!-- }}} -->
</partintro>
&language.predefined.weakmap.count;
&language.predefined.weakmap.getiterator;
&language.predefined.weakmap.offsetexists;
&language.predefined.weakmap.offsetget;
&language.predefined.weakmap.offsetset;
&language.predefined.weakmap.offsetunset;
</reference>
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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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