118 lines
10 KiB
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118 lines
10 KiB
HTML
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<title>std::experimental::make_unique_resource_checked</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_unique_resource_make_unique_resource_checked skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::experimental::</span>make_unique_resource_checked</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-unique_resource.html">unique resource</a></span></div>
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<div>定义于头文件 <code><a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/header/experimental/scope&action=edit&redlink=1" class="new" title="cpp/header/experimental/scope（页面不存在）"><experimental/scope></a></code></div>
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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> R, <span class="kw1">class</span> D, <span class="kw1">class</span> S <span class="sy1">=</span> <a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>R<span class="sy1">>></span><br /></span>
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<p>std<span class="sy4">::</span><span class="me2">experimental</span><span class="sy4">::</span><span class="me2">unique_resource</span><span class="sy1"><</span><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>R<span class="sy1">></span>, <a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>D<span class="sy1">>></span><br />
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make_unique_resource_checked<span class="br0">(</span>R<span class="sy3">&&</span> r, <span class="kw4">const</span> S<span class="sy3">&</span> invalid, D<span class="sy3">&&</span> d<span class="br0">)</span><br /></p>
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<span class="kw1">noexcept</span><span class="br0">(</span><span class="coMULTI">/*see below*/</span><span class="br0">)</span><span class="sy4">;</span></div>
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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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<p>创建 <code>unique_resource</code> ，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>R<span class="sy1">></span><span class="br0">(</span>r<span class="br0">)</span></span></span> 初始化其存储的资源柄，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>D<span class="sy1">></span><span class="br0">(</span>d<span class="br0">)</span></span></span> 初始化其删除器。创建的 <code>unique_resource</code> 占有资源当且仅当 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>r <span class="sy1">==</span> invalid<span class="br0">)</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 。</p>
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<p>若 <span class="t-c"><span class="mw-geshi cpp source-cpp">r <span class="sy1">==</span> invalid</span></span> 不能<a href="cpp-language-implicit_conversion.html#.E6.8C.89.E8.AF.AD.E5.A2.83.E8.BD.AC.E6.8D.A2">按语境转换成 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span></a>，则程序为谬构，而若该转换导致未定义行为或抛异常，则行为未定义。</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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<td>r</td>
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<td>-</td>
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<td>资源柄</td>
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<td>d</td>
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<td>-</td>
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<td>用于释放资源的删除器</td>
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<td>invalid</td>
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<td>-</td>
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<td>指示资源柄为非法的值</td>
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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>如上所述的 <code>unique_resource</code> 。</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>存储的资源柄与删除器的初始化中抛出的任何异常。</p>
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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><br /></span></span>
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<p> <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><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>R<span class="sy1">></span>, R<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><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>D<span class="sy1">></span>, D<span class="sy1">></span><br /></p>
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<span class="br0">)</span></div>
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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><code>make_unique_resource_checked</code> 存在是为了避免以非法参数调用删除器函数。</p>
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<p>复制或移动资源柄 <code>r</code> 到返回值中，而创建的 <code>unique_resource</code> 始终保有拥有对象类型的底层资源柄。</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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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <cstdio></span>
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<span class="co2">#include <experimental/scope></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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<span class="co1">// 避免在 fclose 失败时调用 fclose</span>
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<span class="kw4">auto</span> file <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">experimental</span><span class="sy4">::</span><span class="me2">make_unique_resource_checked</span><span class="br0">(</span>
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<a href="cpp-io-c-fopen.html"><span class="kw1813">std::<span class="me2">fopen</span></span></a><span class="br0">(</span><span class="st0">"potentially_nonexistent_file.txt"</span>, <span class="st0">"r"</span><span class="br0">)</span>,
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nullptr,
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<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><a href="cpp-io-c.html"><span class="kw1877">std::<span class="me2">FILE</span></span></a> <span class="sy2">*</span>fptr<span class="br0">)</span><span class="br0">{</span> <a href="cpp-io-c-fclose.html"><span class="kw1816">std::<span class="me2">fclose</span></span></a><span class="br0">(</span>fptr<span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span>
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<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span>file.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-c-puts.html"><span class="kw1830">std::<span class="me2">puts</span></span></a><span class="br0">(</span><span class="st0">"The file exits."</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">else</span> <span class="br0">{</span>
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<a href="cpp-io-c-puts.html"><span class="kw1830">std::<span class="me2">puts</span></span></a><span class="br0">(</span><span class="st0">"The file does not exist."</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出：</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">The file does not exist.</pre></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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