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weakmap.xml
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133 lines (116 loc) · 3.67 KB
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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- EN-Revision: c4650e160398873696e59305a11db9645e0b7304 Maintainer: mowangjuanzi Status: ready -->
<!-- CREDITS: Luffy -->
<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>WeakMap 类</title>
<titleabbrev>WeakMap</titleabbrev>
<partintro>
<!-- {{{ WeakMap intro -->
<section xml:id="weakmap.intro">
&reftitle.intro;
<para>
<classname>WeakMap</classname> 是将对象作为 key 来访问的 map（或者说字典）。然而，与其它类似 <classname>SplObjectStorage</classname>
不同，<classname>WeakMap</classname> 中的对象 key 不影响对象的引用计数。也就是说，如果在任何时候对其唯一的剩余引用是
<classname>WeakMap</classname> key，那么该对象将会被垃圾收集并从 <classname>WeakMap</classname>
移除。它的主要用法是从对象中编译数据派生缓存，这种场景下不需要存活得比对象更久。
</para>
<para>
<classname>WeakMap</classname> 实现了 <interfacename>ArrayAccess</interfacename>、
<interfacename>Traversable</interfacename>（通过 <interfacename>IteratorAggregate</interfacename>）和
<interfacename>Countable</interfacename>，
因此大多数情况下，它能和关联数组一样使用。
</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> 用法示例</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>
<!-- 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
-->