191 lines
18 KiB
HTML
191 lines
18 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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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<title>std::experimental::function<R(Args...)>::function</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_function_function skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::experimental::function<R(Args...)>::</span>function</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-experimental.html">experimental</a>‎ | <a href="cpp-experimental-function.html">function</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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<div><span class="mw-geshi cpp source-cpp">function<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>(1)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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<tr class="t-dcl t-since-libfund_ts">
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<div><span class="mw-geshi cpp source-cpp">function<span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <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>(2)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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<tr class="t-dcl t-since-libfund_ts">
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<div><span class="mw-geshi cpp source-cpp">function<span class="br0">(</span> <span class="kw4">const</span> function<span class="sy3">&</span> other <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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<tr class="t-dcl t-since-libfund_ts">
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<div><span class="mw-geshi cpp source-cpp">function<span class="br0">(</span> function<span class="sy3">&&</span> other <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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</tr>
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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> F <span class="sy1">></span><br />
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function<span class="br0">(</span> F f <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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</tr>
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<tr class="t-dcl t-since-libfund_ts">
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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> Alloc <span class="sy1">></span><br />
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function<span class="br0">(</span> <a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, <span class="kw4">const</span> Alloc<span class="sy3">&</span> alloc <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>(6)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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</tr>
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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> Alloc <span class="sy1">></span><br /></span>
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<p>function<span class="br0">(</span> <a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, <span class="kw4">const</span> Alloc<span class="sy3">&</span> alloc,<br /></p>
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<a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(7)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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</tr>
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<tr class="t-dcl t-since-libfund_ts">
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<td>
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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> Alloc <span class="sy1">></span><br /></span>
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<p>function<span class="br0">(</span> <a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, <span class="kw4">const</span> Alloc<span class="sy3">&</span> alloc,<br /></p>
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<span class="kw4">const</span> function<span class="sy3">&</span> other <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(8)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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</tr>
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<tr class="t-dcl t-since-libfund_ts">
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<td>
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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> Alloc <span class="sy1">></span><br /></span>
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<p>function<span class="br0">(</span> <a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, <span class="kw4">const</span> Alloc<span class="sy3">&</span> alloc,<br /></p>
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function<span class="sy3">&&</span> other <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(9)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</span></td>
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</tr>
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<tr class="t-dcl t-since-libfund_ts">
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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> F, <span class="kw1">class</span> Alloc <span class="sy1">></span><br />
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function<span class="br0">(</span> <a href="cpp-memory-allocator_arg_t.html"><span class="kw702">std::<span class="me2">allocator_arg_t</span></span></a>, <span class="kw4">const</span> Alloc<span class="sy3">&</span> alloc, F f <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(10)</td>
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<td><span class="t-mark-rev t-since-libfund-ts t-mark-ts">(库基础 TS)</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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</table>
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<p>从各种源构造 <code>std::experimental::function</code> 。</p>
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<div class="t-li1"><span class="t-li">1-2)</span> 构造<i>空</i> function 。</div>
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<div class="t-li1"><span class="t-li">3-4)</span> 复制 <span class="t-v">(3)</span> 或移动 <span class="t-v">(4)</span> <code>other</code> 的<i>目标</i>到 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的<i>目标</i>。若 <code>other</code> 为<i>空</i>，则调用后 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 将亦为<i>空</i>。</div>
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<div class="t-li1"><span class="t-li">5)</span> 以 <code>f</code> 的副本初始化<i>目标</i>。若 <code>f</code> 是指向函数的空指针或指向成员的空指针，则调用后 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 将为<i>空</i>。此构造函数仅若 f 对参数类型 <code>Args...</code> 和返回类型 <code>R</code> <a href="cpp-named_req-Callable.html"><span style="font-style:italic">可调用</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Callable)</span></a> 才参与重载决议。</div>
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<div class="t-li1"><span class="t-li">6-10)</span> 同 <span class="t-v">(1-5)</span> ，除了用 <code>alloc</code> 分配 <code>function</code> 可能使用的任何内部数据结构的内存。这些构造函数将 <code>alloc</code> 当做类型擦除的分配器。</div>
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<p><i>目标</i>为函数指针或 <span class="t-lc"><a href="cpp-utility-functional-reference_wrapper.html">std::reference_wrapper</a></span> 时，保证小对象优化，即始终直接存储这些目标于 <span class="t-lc">std::experimental::function</span> 对象内，不发生动态分配。其他大对象可能在动态分配的存储中构造，并由 <span class="t-lc">std::experimental::function</span> 对象通过指针访问。</p>
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<p>若构造函数移动或复制函数对象，包含 <code>std::experimental::function</code> 的实例，则由<a href="cpp-memory-uses_allocator.html"><i>使用分配器构造</i></a>用分配器 <code>this->get_memory_resource()</code> 进行移动或复制。</p>
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<h3><span class="mw-headline" id=".E7.B1.BB.E5.9E.8B.E6.93.A6.E9.99.A4.E7.9A.84.E5.88.86.E9.85.8D.E5.99.A8">类型擦除的分配器</span></h3>
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<p><code>function</code> 的接收分配器参数 <code>alloc</code> 的构造函数将参数当做类型擦除的分配器。以分配器参数（若指定）确定 <code>function</code> 用来分配内存的 memory_resource 指针，如下：</p>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td><code>alloc</code> 的类型</td>
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<td>memory_resource 指针的值</td>
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</tr>
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<tr class="t-dsc">
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<td>不存在（构造时不指定分配器）</td>
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<td>构造时 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="http://zh.cppreference.com/w/cpp/experimental/get_default_resource"><span class="kw2312">std::<span class="me2">experimental</span><span class="sy4">::</span><span class="me2">pmr</span><span class="sy4">::</span><span class="me2">get_default_resource</span></span></a><span class="br0">(</span><span class="br0">)</span></span></span> 的值。</td>
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</tr>
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<tr class="t-dsc">
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<td><span class="t-lc"><a href="cpp-types-nullptr_t.html">std::nullptr_t</a></span></td>
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<td>构造时 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="http://zh.cppreference.com/w/cpp/experimental/get_default_resource"><span class="kw2312">std::<span class="me2">experimental</span><span class="sy4">::</span><span class="me2">pmr</span><span class="sy4">::</span><span class="me2">get_default_resource</span></span></a><span class="br0">(</span><span class="br0">)</span></span></span> 的值。</td>
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</tr>
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<tr class="t-dsc">
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<td>可转换为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="http://zh.cppreference.com/w/cpp/experimental/memory_resource"><span class="kw2304">std::<span class="me2">experimental</span><span class="sy4">::</span><span class="me2">pmr</span><span class="sy4">::</span><span class="me2">memory_resource</span></span></a><span class="sy2">*</span></span></span><br />
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的指针类型</td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">static_cast</span><span class="sy1"><</span><a href="http://zh.cppreference.com/w/cpp/experimental/memory_resource"><span class="kw2304">std::<span class="me2">experimental</span><span class="sy4">::</span><span class="me2">pmr</span><span class="sy4">::</span><span class="me2">memory_resource</span></span></a><span class="sy2">*</span><span class="sy1">></span><span class="br0">(</span>alloc<span class="br0">)</span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><span class="t-lc"><a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/experimental/polymorphic_allocator&action=edit&redlink=1" class="new" title="cpp/experimental/polymorphic allocator（页面不存在）">std::experimental::pmr::polymorphic_allocator</a></span><br />
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的特化</td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">alloc.<span class="me1">resource</span><span class="br0">(</span><span class="br0">)</span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td>任何其他符合<a href="cpp-named_req-Allocator.html"><span style="font-style:italic">分配器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Allocator)</span></a> 要求的类型</td>
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<td>指向 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-experimental-resource_adaptor.html"><span class="kw2309">std::<span class="me2">experimental</span><span class="sy4">::</span><span class="me2">pmr</span><span class="sy4">::</span><span class="me2">resource_adaptor</span></span></a><span class="sy1"><</span>A<span class="sy1">></span><span class="br0">(</span>alloc<span class="br0">)</span></span></span> 类型对象的指针，其中 <code>A</code> 是 <code>alloc</code> 的类型。指针仅在 <code>function</code> 对象的生存期内保持合法。</td>
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</tr>
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<tr class="t-dsc">
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<td>非以上类型</td>
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<td>程序为病式</td>
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</tr>
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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>other</td>
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<td>-</td>
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<td>用于初始化 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的函数对象</td>
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</tr>
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<tr class="t-par">
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<td>f</td>
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<td>-</td>
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<td>用于初始化 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的可调用对象</td>
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</tr>
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<tr class="t-par">
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<td>alloc</td>
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<td>-</td>
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<td>用于内部内存分配的分配器</td>
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</tr>
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<tr class="t-par-hitem">
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<td colspan="3">类型要求</td>
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</tr>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>F</code> 必须满足<a href="cpp-named_req-Callable.html"><span style="font-style:italic">可调用</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Callable)</span></a> 和 <a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">可复制构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyConstructible)</span></a> 的要求。</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<div class="t-li1"><span class="t-li">3,8)</span> 若 <code>other</code> 的<i>目标</i>是函数指针或 <span class="t-lc"><a href="cpp-utility-functional-reference_wrapper.html">std::reference_wrapper</a></span> 则不抛出，否则可能抛出 <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></span> 或存储的可调用对象的复制构造函数所抛出的任何异常。</div>
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<div class="t-li1"><span class="t-li">4)</span> （无）</div>
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<div class="t-li1"><span class="t-li">5,10)</span> 若 <code>f</code> 是函数指针或 <span class="t-lc"><a href="cpp-utility-functional-reference_wrapper.html">std::reference_wrapper</a></span> 则不抛出，否则可能抛出 <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></span> 或存储的可调用对象的复制构造函数所抛出的任何异常。</div>
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<div class="t-li1"><span class="t-li">9)</span> （无）</div>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
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<tr>
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<td class="mbox-empty-cell"></td>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</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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</div>
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</div>
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</body>
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</html>
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