74 lines
6.0 KiB
HTML
74 lines
6.0 KiB
HTML
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<title>std::experimental::ranges::DerivedFrom</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_ranges_concepts_DerivedFrom 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::ranges::</span>DerivedFrom</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-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-experimental-ranges-concepts.html"><experimental/ranges/concepts></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> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p>concept <span class="kw4">bool</span> DerivedFrom <span class="sy1">=</span><br />
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<a href="cpp-types-is_base_of.html"><span class="kw590">std::<span class="me2">is_base_of</span></span></a><span class="sy1"><</span>U, T<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span> <span class="sy3">&&</span><br /></p>
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<a href="cpp-types-is_convertible.html"><span class="kw592">std::<span class="me2">is_convertible</span></span></a><span class="sy1"><</span><a href="cpp-types-remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy2">*</span>, <a href="cpp-types-remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy2">*</span><span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-ranges-ts t-mark-ts">(范围 TS)</span></td>
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<p>概念 <span class="t-c"><span class="mw-geshi cpp source-cpp">DerivedFrom<span class="sy1"><</span>T, U<span class="sy1">></span></span></span> 若且唯若 <code>U</code> 为类类型且为 <code>T</code> 或 <code>T</code> 的无歧义公开基类才得到满足。</p>
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<p>无关乎在其上述描述中使用 <span class="t-lc"><a href="cpp-types-is_base_of.html">std::is_base_of</a></span> 和 <span class="t-lc"><a href="cpp-types-is_convertible.html">std::is_convertible</a></span> 。不要求 <code>DerivedFrom</code> 在其实现中使用用它们。故而 <span class="t-c"><span class="mw-geshi cpp source-cpp">DerivedFrom<span class="sy1"><</span>T, U<span class="sy1">></span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_base_of.html"><span class="kw590">std::<span class="me2">is_base_of</span></span></a><span class="sy1"><</span>U,T<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_convertible.html"><span class="kw592">std::<span class="me2">is_convertible</span></span></a><span class="sy1"><</span><a href="cpp-types-remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy2">*</span>, <a href="cpp-types-remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy2">*</span><span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span></span></span> 间不必有任何蕴含关系。</p>
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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><a href="cpp-types-is_base_of.html"><span class="t-lines"><span>is_base_of</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>检查一个类型是否派生自另一个类型<br />
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<span class="t-mark">(类模板)</span></td>
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<div><a href="cpp-types-is_convertible.html"><span class="t-lines"><span>is_convertible</span><span>is_nothrow_convertible</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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<td>检查是否能转换一个类型为另一类型<br />
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<span class="t-mark">(类模板)</span></td>
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