66 lines
7.6 KiB
HTML
66 lines
7.6 KiB
HTML
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<title>std::out_ptr_t<Smart,Pointer,Args...>::~out_ptr_t</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::out_ptr_t<Smart,Pointer,Args...>::</span>~out_ptr_t</h1>
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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-out_ptr_t.html">out ptr t</a></span></div>
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<div><span class="mw-geshi cpp source-cpp">~out_ptr_t<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx23">(C++23 起)</span></td>
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<p>以修改的 <code>Pointer</code> 对象（或若调用了 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator <span class="kw4">void</span><span class="sy2">**</span><span class="br0">(</span><span class="br0">)</span></span></span> 则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span><span class="sy2">*</span></span></span> 对象）的值捕获的实参重设适配的 <code>Smart</code> 对象。</p>
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<p>令</p>
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<ul>
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<li><code>s</code> 代表适配的 <code>Smart</code> 对象，</li>
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<li><code>args...</code> 代表捕获的实参，</li>
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<li><code>p</code> 代表存储的 <code>Pointer</code> 的值，或若调用了 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator <span class="kw4">void</span><span class="sy2">**</span></span></span> 则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">static_cast</span><span class="sy1"><</span>Pointer<span class="sy1">></span><span class="br0">(</span><span class="sy2">*</span>operator <span class="kw4">void</span><span class="sy2">**</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> ，</li>
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<li><code>SP</code> 为
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">Smart<span class="sy4">::</span><span class="me2">pointer</span></span></span> ，若它合法并代表类型，否则为</li>
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<li><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> 并代表类型，否则为</li>
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<li><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> ，若 <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></span> 合法并代表类型，否则为</li>
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<li><code>Pointer</code> 。</li>
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</ul>
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</li>
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</ul>
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<p>若 <span class="t-c"><span class="mw-geshi cpp source-cpp">s.<span class="me1">reset</span><span class="br0">(</span><span class="kw1">static_cast</span><span class="sy1"><</span>SP<span class="sy1">></span><span class="br0">(</span>p<span class="br0">)</span>, <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> 为良构，则析构函数进行</p>
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<dd><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">if</span> <span class="br0">(</span>p<span class="br0">)</span> s.<span class="me1">reset</span><span class="br0">(</span><span class="kw1">static_cast</span><span class="sy1"><</span>SP<span class="sy1">></span><span class="br0">(</span>p<span class="br0">)</span>, <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 class="sy4">;</span></span></span> ，</dd>
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<p>否则，若 <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>Smart, SP, Args...<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> ，则析构函数进行</p>
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<dd><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">if</span> <span class="br0">(</span>p<span class="br0">)</span> s <span class="sy1">=</span> Smart<span class="br0">(</span><span class="kw1">static_cast</span><span class="sy1"><</span>SP<span class="sy1">></span><span class="br0">(</span>p<span class="br0">)</span>, <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 class="sy4">;</span></span></span> ，</dd>
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<p>否则程序非良构。</p>
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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>若 <code>Smart</code> 是 <span class="t-lc"><a href="cpp-memory-shared_ptr.html">std::shared_ptr</a></span> 的特化，则实现可以在构造时分配重设新的控制块的存储，以将不抛出的工作留给析构函数。</p>
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<p>在重设后销毁按值捕获的实参。</p>
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