136 lines
13 KiB
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136 lines
13 KiB
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<title>std::source_location::current</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_utility_source_location_current 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::source_location::</span>current</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-utility.html">utility</a>‎ | <a href="cpp-utility-source_location.html">source location</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">static</span> consteval source_location current<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</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-cxx20">(C++20 起)</span></td>
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<p>构造对应调用位置的新的 <code>source_location</code> 对象。</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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<p>（无）</p>
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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>若直接调用 <code>current()</code> （通过指名 <code>current()</code> 的函数调用），则它返回对应调用位置的拥有实现定义值的 <code>source_location</code> 对象。该值应当以同预定义宏 <span class="t-c"><span class="mw-geshi cpp source-cpp">__LINE__</span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp">__FILE__</span></span> 的方式受 <a href="cpp-preprocessor-line.html"><code>#line</code> 预处理指令</a>影响。</p>
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<p>若在<a href="cpp-language-data_members.html#.E6.88.90.E5.91.98.E5.88.9D.E5.A7.8B.E5.8C.96">默认成员初始化器</a>中使用 <code>current()</code> ，则返回值对应初始化该数据成员的构造函数定义或<a href="cpp-language-aggregate_initialization.html">聚合初始化</a>的位置。</p>
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<p>若 <code>current()</code> 用于默认参数，则返回值对应对 <code>current()</code> 的调用的调用点位置。</p>
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<p>若以任何其他方式调用 <code>current()</code> ，则返回值未指定。</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><code>std::source_location::current</code> 通常要求编译器的内建实现。</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="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 <source_location></span>
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<span class="co2">#include <iostream></span>
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<span class="kw1">struct</span> src_rec <span class="br0">{</span>
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std<span class="sy4">::</span><span class="me2">source_location</span> srcl <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy4">::</span><span class="me2">current</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">int</span> dummy <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
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src_rec<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">source_location</span> loc <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy4">::</span><span class="me2">current</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy4">:</span>
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srcl<span class="br0">(</span>loc<span class="br0">)</span> <span class="co1">// 成员的值指代调用函数的位置</span>
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<span class="br0">{</span><span class="br0">}</span>
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src_rec<span class="br0">(</span><span class="kw4">int</span> i<span class="br0">)</span> <span class="sy4">:</span> <span class="co1">// 成员的值指代此位置</span>
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dummy<span class="br0">(</span>i<span class="br0">)</span>
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<span class="br0">{</span><span class="br0">}</span>
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src_rec<span class="br0">(</span><span class="kw4">double</span><span class="br0">)</span> <span class="co1">// 成员的值指代此位置</span>
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<span class="br0">{</span><span class="br0">}</span>
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<span class="br0">}</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">source_location</span> src_clone<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">source_location</span> a <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy4">::</span><span class="me2">current</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw1">return</span> a<span class="sy4">;</span>
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<span class="br0">}</span>
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std<span class="sy4">::</span><span class="me2">source_location</span> src_make<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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std<span class="sy4">::</span><span class="me2">source_location</span> b <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy4">::</span><span class="me2">current</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> b<span class="sy4">;</span>
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<span class="br0">}</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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src_rec srec0<span class="sy4">;</span>
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src_rec srec1<span class="br0">(</span><span class="nu0">0</span><span class="br0">)</span><span class="sy4">;</span>
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src_rec srec2<span class="br0">(</span><span class="nu16">0.0</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> s0 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">source_location</span><span class="sy4">::</span><span class="me2">current</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> s1 <span class="sy1">=</span> src_clone<span class="br0">(</span>s0<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> s2 <span class="sy1">=</span> src_clone<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> s3 <span class="sy1">=</span> src_make<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>
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<span class="sy1"><<</span> srec0.<span class="me1">srcl</span>.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> srec0.<span class="me1">srcl</span>.<span class="me1">function_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> srec1.<span class="me1">srcl</span>.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> srec1.<span class="me1">srcl</span>.<span class="me1">function_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> srec2.<span class="me1">srcl</span>.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> srec2.<span class="me1">srcl</span>.<span class="me1">function_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> s0.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> s0.<span class="me1">function_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> s1.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> s1.<span class="me1">function_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> s2.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> s2.<span class="me1">function_name</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> s3.<span class="me1">line</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> s3.<span class="me1">function_name</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></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">31 int main()
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12 src_rec::src_rec(int)
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15 src_rec::src_rec(double)
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34 int main()
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34 int main()
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36 int main()
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25 std::source_location src_make()</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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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-utility-source_location-source_location.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造拥有实现定义的值的新 <code>source_location</code><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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<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-utility-basic_stacktrace-current.html"><span class="t-lines"><span>current</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</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>获得当前栈踪或其给定部分<br />
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<span class="t-mark">(<code>std::basic_stacktrace<Allocator></code> 的公开静态成员函数)</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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