114 lines
7.7 KiB
HTML
114 lines
7.7 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::inout_ptr</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_inout_ptr_t_inout_ptr skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>inout_ptr</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-memory.html">memory</a>‎ | <a href="cpp-memory-inout_ptr_t.html">inout ptr t</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-memory.html"><memory></a></code></div>
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</td>
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<td></td>
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<td></td>
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<tr class="t-dcl t-since-cxx23">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> Pointer <span class="sy1">=</span> <span class="kw4">void</span>, <span class="kw1">class</span> Smart, <span class="kw1">class</span>... <span class="me1">Args</span> <span class="sy1">></span><br />
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<span class="kw4">auto</span> inout_ptr<span class="br0">(</span> Smart<span class="sy3">&</span> s, Args<span class="sy3">&&</span>... <span class="me1">args</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx23">(C++23 起)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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<p>返回拥有被推导模板实参的 <code>inout_ptr_t</code> ，按引用绑定重设用的实参。</p>
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<p>若返回值（见后述）的构造非良构则程序非良构。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>s</td>
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<td>-</td>
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<td>要适配的对象（常为智能指针）</td>
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</tr>
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<tr class="t-par">
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<td>args...</td>
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<td>-</td>
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<td>要捕获的用于重设的实参</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">inout_ptr_t</span><span class="sy1"><</span>Smart, P, Args<span class="sy3">&&</span><span class="sy1">></span><span class="br0">(</span>s, <a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>Args<span class="sy1">></span><span class="br0">(</span>args<span class="br0">)</span>...<span class="br0">)</span></span></span> ，其中 <code>P</code> 为</p>
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<ul>
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<li><code>Pointer</code> ，若 <code>Pointer</code> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span></span></span> 不同，</li>
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<li>否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">Smart<span class="sy4">::</span><span class="me2">pointer</span></span></span> ，若它合法并指代类型，</li>
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<li>否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">Smart<span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span></span></span> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp">Smart<span class="sy4">::</span><span class="me2">element_type</span></span></span> 合法并指代类型，</li>
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<li>否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-pointer_traits.html"><span class="kw756">std::<span class="me2">pointer_traits</span></span></a><span class="sy1"><</span>Smart<span class="sy1">></span><span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span></span></span> 。</li>
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</ul>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>用户可对模板形参 <code>Pointer</code> 指定模板实参，以与接收 <span class="t-c"><span class="mw-geshi cpp source-cpp">Pointer<span class="sy2">*</span></span></span> 的外来函数交互。</p>
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<p>由于所有实参都按引用捕获，返回的 <code>inout_ptr_t</code> 应为在含有外来函数调用的全表达式结尾销毁的临时对象，以避免悬垂引用。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
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<td class="mbox-empty-cell"></td>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</td>
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</tr>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div class="t-dsc-member-div">
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<div><a href="cpp-memory-out_ptr_t-out_ptr.html"><span class="t-lines"><span>out_ptr</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx23">(C++23)</span></span></span></div>
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</div>
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</td>
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<td>以关联的智能指针和重设参数创建 <code>out_ptr_t</code><br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-memory-unique_ptr-make_unique.html"><span class="t-lines"><span>make_unique</span><span>make_unique_for_overwrite</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>创建管理一个新对象的独占指针<br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-memory-shared_ptr-make_shared.html"><span class="t-lines"><span>make_shared</span><span>make_shared_for_overwrite</span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>创建管理一个新对象的共享指针<br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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