113 lines
8.9 KiB
HTML
113 lines
8.9 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::promise<R>::set_exception</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_thread_promise_set_exception 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::promise<R>::</span>set_exception</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-thread.html">thread</a>‎ | <a href="cpp-thread-promise.html">promise</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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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> set_exception<span class="br0">(</span> <a href="cpp-error-exception_ptr.html"><span class="kw776">std::<span class="me2">exception_ptr</span></span></a> p <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-cxx11">(C++11 起)</span></td>
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</tr>
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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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</tr>
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</tbody>
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</table>
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<p>存储异常指针 <code>p</code> 到共享状态中，并令状态就绪。</p>
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<p><span class="t-lc"><a href="cpp-thread-promise-set_value.html">set_value</a></span> 、 <code>set_exception</code> 、 <span class="t-lc"><a href="cpp-thread-promise-set_value_at_thread_exit.html">set_value_at_thread_exit</a></span> 和 <span class="t-lc"><a href="cpp-thread-promise-set_exception_at_thread_exit.html">set_exception_at_thread_exit</a></span> 的操作表现类似。在更新 promise 对象时获得单个与 promise 对象关联的互斥。</p>
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<p>若无共享状态，或共享状态已存储值或异常，则抛出异常。</p>
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<p>对此函数的调用和对 <span class="t-lc"><a href="cpp-thread-promise-get_future.html">get_future</a></span> 的调用不会造成数据竞争（但它们不需要彼此同步）。</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>p</td>
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<td>-</td>
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<td>要存储的异常指针。若 <code>p</code> 为空则行为未定义。</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>（无）</p>
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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>遇到下列条件时为 <span class="t-lc"><a href="cpp-thread-future_error.html">std::future_error</a></span> ：</p>
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 无共享状态。设置 error_category 为 <a href="cpp-thread-future_errc.html"><tt>no_state</tt></a> 。</li>
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</ul>
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<ul>
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<li>共享状态已存储值或异常。设置 error_category 为 <a href="cpp-thread-future_errc.html"><tt>promise_already_satisfied</tt></a> 。</li>
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</ul>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <thread></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <future></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-thread-promise.html"><span class="kw2179">std::<span class="me2">promise</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> p<span class="sy4">;</span>
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<a href="cpp-thread-future.html"><span class="kw2180">std::<span class="me2">future</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> f <span class="sy1">=</span> p.<span class="me1">get_future</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-thread-thread.html"><span class="kw2146">std::<span class="me2">thread</span></span></a> t<span class="br0">(</span><span class="br0">[</span><span class="sy3">&</span>p<span class="br0">]</span><span class="br0">{</span>
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<span class="kw1">try</span> <span class="br0">{</span>
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<span class="co1">// 可能抛出的代码</span>
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<span class="kw1">throw</span> <a href="cpp-error-runtime_error.html"><span class="kw770">std::<span class="me2">runtime_error</span></span></a><span class="br0">(</span><span class="st0">"Example"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">catch</span><span class="br0">(</span>...<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">try</span> <span class="br0">{</span>
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<span class="co1">// 存储任何抛出的异常于 promise</span>
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p.<span class="me1">set_exception</span><span class="br0">(</span><a href="cpp-error-current_exception.html"><span class="kw778">std::<span class="me2">current_exception</span></span></a><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">catch</span><span class="br0">(</span>...<span class="br0">)</span> <span class="br0">{</span><span class="br0">}</span> <span class="co1">// set_exception() 亦可能抛出</span>
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<span class="br0">}</span>
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<span class="br0">}</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">try</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> f.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">catch</span><span class="br0">(</span><span class="kw4">const</span> <a href="cpp-error-exception.html"><span class="kw764">std::<span class="me2">exception</span></span></a><span class="sy3">&</span> e<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Exception from the thread: "</span> <span class="sy1"><<</span> e.<span class="me1">what</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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t.<span class="me1">join</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">Exception from the thread: Example</pre></div>
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</div>
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</div>
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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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<div class="t-dsc-member-div">
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<div><a href="cpp-thread-promise-set_exception_at_thread_exit.html"><span class="t-lines"><span>set_exception_at_thread_exit</span></span></a></div>
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</div>
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</td>
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<td>设置结果为指示异常，同时仅在线程退出时分发提醒<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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</body>
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