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weakreference.xml
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131 lines (114 loc) · 3.56 KB
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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- EN-Revision: 7caf0c13762e7db3e7002b1286f23b65d940e2d0 Maintainer: daijie Status: ready -->
<!-- CREDITS: mowangjuanzi -->
<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>WeakReference 类</title>
<titleabbrev>WeakReference</titleabbrev>
<partintro>
<!-- {{{ WeakReference intro -->
<section xml:id="weakreference.intro">
&reftitle.intro;
<para>
弱引用允许保留对对象的引用，而不会阻止销毁对象。对于实现类似缓存的结构很有用。如果原始对象已销毁，则调用
<methodname>WeakReference::get</methodname> 方法时将返回 &null;。当原始对象的 <link
linkend="features.gc.refcounting-basics">refcount</link> 降至零时，会销毁原始对象；创建弱引用不会增加被引用对象的
<literal>refcount</literal>。
</para>
<para>
<classname>弱引用类</classname>不能序列化。
</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>弱引用示例</title>
<para>
<example xml:id="weakreference.basic-example">
<title>弱引用的基础用法</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>
<section role="changelog">
&reftitle.changelog;
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>8.4.0</entry>
<entry>
现在 <methodname>WeakReference::__debugInfo</methodname>
的输出包含引用的对象，当引用不可用时，为 <literal>NULL</literal>。
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</section>
</partintro>
&language.predefined.weakreference.construct;
&language.predefined.weakreference.create;
&language.predefined.weakreference.get;
</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
-->