122 lines
14 KiB
HTML
122 lines
14 KiB
HTML
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<title>std::experimental::scope_exit<EF>::scope_exit</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_scope_exit_scope_exit skin-cppreference2 action-view cpp-page-template cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::experimental::scope_exit<EF>::</span>scope_exit</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-experimental.html">experimental</a>‎ | <a href="cpp-experimental-scope_exit.html">scope exit</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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<p></p>
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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> Fn<span class="sy1">></span><br />
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<span class="kw1">explicit</span> scope_exit<span class="br0">(</span> Fn<span class="sy3">&&</span> fn <span class="br0">)</span> <span class="kw1">noexcept</span><span class="br0">(</span><span class="coMULTI">/*see below*/</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-libfund-ts-3 t-mark-ts">(库基础 TS v3)</span></td>
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<div><span class="mw-geshi cpp source-cpp">scope_exit<span class="br0">(</span> scope_exit<span class="sy3">&&</span> other <span class="br0">)</span> <span class="kw1">noexcept</span><span class="br0">(</span><span class="coMULTI">/*see below*/</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-libfund-ts-3 t-mark-ts">(库基础 TS v3)</span></td>
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<div><span class="mw-geshi cpp source-cpp">scope_exit<span class="br0">(</span> <span class="kw4">const</span> scope_exit<span class="sy3">&</span> <span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-libfund-ts-3 t-mark-ts">(库基础 TS v3)</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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<p>从函数、函数对象或另一 <code>scope_exit</code> 创建 <code>scope_exit</code> 。</p>
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<div class="t-li1"><span class="t-li">1)</span> 以函数或函数对象初始化退出函数。构造的 <code>scope_exit</code> 为活跃。</div>
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<div class="t-li1"><span class="t-li"></span> 若 <code>Fn</code> 不是左值引用类型且 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw525">std::<span class="me2">is_nothrow_constructible_v</span></span></a><span class="sy1"><</span>EF, Fn<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，则以 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>Fn<span class="sy1">></span><span class="br0">(</span>fn<span class="br0">)</span></span></span> ，否则以 <span class="t-c"><span class="mw-geshi cpp source-cpp">fn</span></span> 初始化存储的 <code>EF</code> 。</div>
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<div class="t-li1"><span class="t-li"></span> 若初始化存储的 <code>EF</code> 抛异常，则调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">fn<span class="br0">(</span><span class="br0">)</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li"></span> 此重载仅若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_same.html"><span class="kw589">std::<span class="me2">is_same_v</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">remove_cvref_t</span><span class="sy1"><</span>Fn<span class="sy1">></span>, scope_exit<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 且 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_constructible.html"><span class="kw521">std::<span class="me2">is_constructible_v</span></span></a><span class="sy1"><</span>EF, Fn<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 才参与重载决议。</div>
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<div class="t-li1"><span class="t-li"></span> 若函数调用表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">fn<span class="br0">(</span><span class="br0">)</span></span></span> 为谬构，则程序为谬构。</div>
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<div class="t-li1"><span class="t-li"></span> 若调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">fn<span class="br0">(</span><span class="br0">)</span></span></span> 抛出异常或导致未定义行为，则行为未定义，即使未调用 <code>fn</code> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 移动构造函数。以 <code>other</code> 的存储的 <code>EF</code> 初始化存储的 <code>EF</code> 。构造的 <code>scope_exit</code> 为活跃当且仅当 <code>other</code> 在构造前活跃。</div>
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<div class="t-li1"><span class="t-li"></span> 若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_move_constructible.html"><span class="kw543">std::<span class="me2">is_nothrow_move_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，则以 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span><span class="br0">(</span>other.<span class="me1">exitfun</span><span class="br0">)</span></span></span> ，否则以 <span class="t-c"><span class="mw-geshi cpp source-cpp">other.<span class="me1">exitfun</span></span></span> 初始化存储的 <code>EF</code> （以 <code>exitfun</code> 代表）。</div>
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<div class="t-li1"><span class="t-li"></span> 在成功移动构造后调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">other.<span class="me1">release</span><span class="br0">(</span><span class="br0">)</span></span></span> 而 <code>other</code> 变为不活跃。</div>
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<div class="t-li1"><span class="t-li"></span> 此重载仅若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_move_constructible.html"><span class="kw543">std::<span class="me2">is_nothrow_move_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_copy_constructible.html"><span class="kw533">std::<span class="me2">is_copy_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 才参与重载决议。</div>
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<div class="t-li1"><span class="t-li"></span> 若有下列情况则行为未定义
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_move_constructible.html"><span class="kw543">std::<span class="me2">is_nothrow_move_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 而 <code>EF</code> 不满足<a href="cpp-named_req-MoveConstructible.html"><span style="font-style:italic">可移动构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(MoveConstructible)</span></a> 的要求，或</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_move_constructible.html"><span class="kw543">std::<span class="me2">is_nothrow_move_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 而 <code>EF</code> 不满足<a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">可复制构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyConstructible)</span></a> 的要求。</li>
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</ul>
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</div>
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<div class="t-li1"><span class="t-li">3)</span> <code>scope_exit</code> 非<a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">可复制构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyConstructible)</span></a> 。</div>
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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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<td>fn</td>
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<td>-</td>
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<td>用于初始化存储的 <code>EF</code> 的函数或函数对象</td>
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</tr>
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<tr class="t-par">
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<td>other</td>
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<td>-</td>
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<td>要移动的 <code>scope_exit</code></td>
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</tr>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>初始化存储的 <code>EF</code> 期间抛出的任何异常。</p>
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<div class="t-li1"><span class="t-li">1)</span>
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<div class="t-noexcept-full"><a href="cpp-language-noexcept_spec.html"><tt>noexcept</tt></a> 说明：
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<div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span><span class="br0">(</span><a href="cpp-types-is_constructible.html"><span class="kw525">std::<span class="me2">is_nothrow_constructible_v</span></span></a><span class="sy1"><</span>EF, Fn<span class="sy1">></span> <span class="sy3">||</span><br />
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<a href="cpp-types-is_constructible.html"><span class="kw525">std::<span class="me2">is_nothrow_constructible_v</span></span></a><span class="sy1"><</span>EF, Fn<span class="sy3">&</span><span class="sy1">></span><span class="br0">)</span></span></span></div>
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</div>
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</div>
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<div class="t-li1"><span class="t-li">2)</span>
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<div class="t-noexcept-full"><a href="cpp-language-noexcept_spec.html"><tt>noexcept</tt></a> 说明：
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<div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span><span class="br0">(</span><a href="cpp-types-is_move_constructible.html"><span class="kw543">std::<span class="me2">is_nothrow_move_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span> <span class="sy3">||</span><br />
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<a href="cpp-types-is_copy_constructible.html"><span class="kw537">std::<span class="me2">is_nothrow_copy_constructible_v</span></span></a><span class="sy1"><</span>EF<span class="sy1">></span><span class="br0">)</span></span></span></div>
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</div>
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</div>
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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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</table>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-experimental-scope_exit-release.html"><span class="t-lines"><span>release</span></span></a></div>
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</div>
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</td>
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<td>使 <code>scope_exit</code> 不活跃<br />
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<span class="t-mark">(公开成员函数)</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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