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<header data-kunai-mdinfo="{"meta": {"header": ["functional"], "id-type": ["class template"], "namespace": ["std"], "cpp": ["cpp26"]}, "sources": [{"id": "4dadadcd2c809225636bf18eefcf122dfef40be6", "source": "#include <functional>\n#include <iostream>\n\nint add(int x) { return x + 1; }\n\nint main()\n{\n // \u95a2\u6570\u3092\u4ee3\u5165\n std::copyable_function<int(int)> f = add;\n\n // \u95a2\u6570\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4ee3\u5165\n f = [](int x) { return x + 1; };\n\n // \u4fdd\u6301\u3057\u3066\u3044\u308b\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\n int result = f(1);\n std::cout << result << std::endl;\n}\n"}, {"id": "a89526c11534b9a266103f01c5b5e756c37f27ee", "source": "#include <functional>\n#include <iostream>\n#include <string>\n#include <utility>\n\nstruct Functor {\n std::string operator()() & {\n return \"L-val\";\n }\n std::string operator()() && {\n return \"R-val\";\n }\n};\n\nint main()\n{\n std::cout << \"-- copyable_function\" << std::endl;\n std::copyable_function<std::string(void)> mof1 = Functor{};\n std::copyable_function<std::string(void) &&> mof2 = Functor{};\n std::cout << \"mof1/L-val: \" << mof1() << std::endl;\n std::cout << \"mof1/R-val: \" << std::move(mof1)() << std::endl;\n//std::cout << \"mof2/L-val: \" << mof2() << std::endl; // \u4e0d\u9069\u683c\n std::cout << \"mof2/R-val: \" << std::move(mof2)() << std::endl;\n\n std::cout << \"-- function\" << std::endl;\n std::function<std::string(void)> fn1 = Functor{};\n//std::function<std::string(void) &&> fn2 = Functor{}; // \u4e0d\u9069\u683c\n std::cout << \"fn1/L-val: \" << fn1() << std::endl;\n std::cout << \"fn1/R-val: \" << std::move(fn1)() << std::endl;\n}\n"}, {"id": "3c2bbd5ac34569ea3e8ec47a4906800aa06de429", "source": "#include <functional>\n\nvoid func() {}\nvoid func_noex() noexcept {}\n\nint main()\n{\n std::copyable_function<void(void)> mof1 = func;\n std::copyable_function<void(void)> mof2 = func_noex;\n//std::copyable_function<void(void) noexcept> mof3 = func; // \u4e0d\u9069\u683c\n std::copyable_function<void(void) noexcept> mof4 = func_noex;\n static_assert(not noexcept(mof1()));\n static_assert(not noexcept(mof2()));\n static_assert( noexcept(mof4()));\n\n std::function<void(void)> fn1 = func;\n std::function<void(void)> fn2 = func_noex;\n//std::function<void(void) noexcept> fn3 = func; // \u4e0d\u9069\u683c\n//std::function<void(void) noexcept> fn4 = func_noex; // \u4e0d\u9069\u683c\n static_assert(not noexcept(fn1()));\n static_assert(not noexcept(fn2()));\n}\n"}], "page_id": ["reference", "functional", "copyable_function"]}">
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<div class="identifier-type">class template</div><div class="header"><functional></div><h1 itemprop="name"><span class="namespace" title="namespace std">std::</span><span class="token">copyable_function</span><span class="cpp cpp26" title="C++26で追加">(C++26)</span></h1>
<div itemprop="articleBody"><p><div class="codehilite"><pre><span></span><code><span class="k">namespace</span><span class="w"> </span><span class="nn">std</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">template</span><span class="o"><</span><span class="k">class</span><span class="p">...</span><span class="w"> </span><span class="n">S</span><span class="o">></span>
<span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">copyable_function</span><span class="p">;</span><span class="w"> </span><span class="c1">// 宣言のみ</span>
<span class="w"> </span><span class="k">template</span><span class="o"><</span><span class="k">class</span><span class="w"> </span><span class="nc">R</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="p">...</span><span class="w"> </span><span class="n">ArgTypes</span><span class="o">></span>
<span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">copyable_function</span><span class="o"><</span><span class="n">R</span><span class="p">(</span><span class="n">ArgTypes</span><span class="p">...)</span><span class="w"> </span><span class="cm">/*cv*/</span><span class="w"> </span><span class="cm">/*ref*/</span><span class="w"> </span><span class="k">noexcept</span><span class="p">(</span><span class="cm">/*noex*/</span><span class="p">)</span><span class="o">></span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h2>概要</h2>
<p><code>copyable_function</code>クラステンプレートは、パラメータの型リスト<code>ArgTypes...</code>、<a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型<code>R</code>に合致する、あらゆる関数ポインタ、関数オブジェクト、メンバ関数ポインタ、メンバ変数ポインタを保持できるクラスである。</p>
<p>下記全ての組み合わせ（12種類）に対して、クラステンプレートの部分特殊化が提供される。</p>
<ul>
<li><a class="cpprefjp-defined-word" data-desc="型をconstおよび・もしくはvolatileで修飾すること">CV修飾</a>子 <em>cv</em> : <code>const</code>, <a class="cpprefjp-defined-word" data-desc="型をconstおよび・もしくはvolatileで修飾すること">CV修飾</a>無し</li>
<li>参照修飾子 <em>ref</em> : <code>&</code>, <code>&&</code>, 参照修飾無し</li>
<li>noexcept<a class="cpprefjp-defined-word" data-desc="問題が発生したときに、現在実行位置を過去に通過・記録した位置に戻し、文脈情報を添えて紐づけられた処理(例外ハンドラー)を呼び出す仕組み。またはその事態">例外</a>指定 <em>noex</em> : <code>true</code>, <code>false</code></li>
</ul>
<h3><code>function</code>との比較</h3>
<p><code><a href="function.html">std::function</a></code>と比べて、<code>std::copyable_function</code>は下記の特徴をもつ。</p>
<ul>
<li>関数型の<a class="cpprefjp-defined-word" data-desc="型をconstおよび・もしくはvolatileで修飾すること">CV修飾</a>／参照修飾／noexcept<a class="cpprefjp-defined-word" data-desc="問題が発生したときに、現在実行位置を過去に通過・記録した位置に戻し、文脈情報を添えて紐づけられた処理(例外ハンドラー)を呼び出す仕組み。またはその事態">例外</a>指定をサポートする。<ul>
<li>const性などを正しく伝搬することでバグ発生リスクを軽減する</li>
</ul>
</li>
<li><code><a href="function/target_type.html">target_type</a></code>型と<code><a href="function/target.html">target()</a></code>を提供しない。<ul>
<li>実行時型情報（RTTI）非依存</li>
</ul>
</li>
<li><a href="copyable_function/op_call.html">関数呼び出し</a>は強い<a class="cpprefjp-defined-word" data-desc="関数等の意味論を構成する要素の1つ。Preconditions。関数呼び出し時に満たされていると関数が想定する条件。満たさなければ未定義の動作。契約属性の`[[expects]]`に相当">事前条件</a>を持つ。<ul>
<li>関数呼び出し時のnullチェックが要求されない</li>
</ul>
</li>
<li>クラステンプレート引数の<a href="../../lang/cpp17/type_deduction_for_class_templates.html">推論補助</a>を提供しない。</li>
</ul>
<h2>メンバ関数</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="copyable_function/op_constructor.html">(constructor)</a></code></td>
<td>コンストラクタ</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/op_destructor.html">(destructor)</a></code></td>
<td>デストラクタ</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/op_assign.html">operator=</a></code></td>
<td>代入演算子</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/swap.html">swap</a></code></td>
<td>他の<code>copyable_function</code>オブジェクトと中身を入れ替える</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/op_bool.html">operator bool</a></code></td>
<td>関数呼び出しが可能か調べる</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/op_call.html">operator()</a></code></td>
<td>関数呼び出し</td>
<td>C++26</td>
</tr>
</tbody>
</table>
<h2>メンバ型</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>result_type</code></td>
<td>関数の<a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型(テンプレートパラメータ<code>R</code>)</td>
<td>C++26</td>
</tr>
</tbody>
</table>
<h2>非メンバ関数</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="copyable_function/op_equal.html">operator==</a></code></td>
<td>等値比較</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/op_not_equal.html">operator!=</a></code></td>
<td>非等値比較</td>
<td>C++26</td>
</tr>
<tr>
<td><code><a href="copyable_function/swap_free.html">swap</a></code></td>
<td>2つの<code>copyable_function</code>オブジェクトを入れ替える</td>
<td>C++26</td>
</tr>
</tbody>
</table>
<h2>例</h2>
<h3>例1: 基本の使い方</h3>
<p><div class="yata" id="4dadadcd2c809225636bf18eefcf122dfef40be6"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../functional.html"><functional></a></span>
<span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="kt">int</span><span class="w"> </span><span class="nf">add</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">x</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"> </span><span class="p">}</span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="c1">// 関数を代入</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="kt">int</span><span class="p">(</span><span class="kt">int</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">f</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">add</span><span class="p">;</span>
<span class="w"> </span><span class="c1">// 関数オブジェクトを代入</span>
<span class="w"> </span><span class="n">f</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">[](</span><span class="kt">int</span><span class="w"> </span><span class="n">x</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"> </span><span class="p">};</span>
<span class="w"> </span><span class="c1">// 保持している関数を呼び出す</span>
<span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">result</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="copyable_function/op_call.html">f(1)</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">result</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</div></p>
<h4>出力</h4>
<p><pre><code>2
</code></pre></p>
<h3>例2: const性の伝搬</h3>
<p><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../functional.html"><functional></a></span>
<span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../string.html"><string></a></span>
<span class="cp">#include <a href="../utility.html"><utility></a></span>
<span class="k">struct</span><span class="w"> </span><span class="nc">Functor</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="w"> </span><span class="nf">operator</span><span class="p">()()</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="s">"non-const"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="w"> </span><span class="nf">operator</span><span class="p">()()</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="s">"const"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">};</span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"-- copyable_function"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">mof1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">mof2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span><span class="w"> </span><span class="c1">// (呼び出し時に不適格)</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="o">></span><span class="w"> </span><span class="n">mof3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="w"> </span><span class="k">const</span><span class="o">></span><span class="w"> </span><span class="n">mof4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"mof1: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">mof1</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="c1">//<a href="../iostream/cout.html">std::cout</a> << "mof2: " << mof2() << <a href="../ostream/endl.html">std::endl</a>; // 不適格</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"mof3: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">mof3</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"mof4: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">mof4</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"-- function"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="function.html">std::function</a></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">fn1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n"><a href="function.html">std::function</a></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">fn2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="c1">// <a href="function.html">std::function</a><<a href="../string/basic_string.html">std::string</a>(void) const> fn3 = Functor{}; // 不適格</span>
<span class="c1">//const <a href="function.html">std::function</a><<a href="../string/basic_string.html">std::string</a>(void) const> fn4 = Functor{}; // 不適格</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"fn1: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">fn1</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"fn2: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">fn2</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h4>出力</h4>
<p><pre><code>-- copyable_function
mof1: non-const
mof3: const
mof4: const
-- function
fn1: non-const
fn2: non-const
</code></pre></p>
<h3>例3: 左辺値/右辺値の伝搬</h3>
<p><div class="yata" id="a89526c11534b9a266103f01c5b5e756c37f27ee"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../functional.html"><functional></a></span>
<span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../string.html"><string></a></span>
<span class="cp">#include <a href="../utility.html"><utility></a></span>
<span class="k">struct</span><span class="w"> </span><span class="nc">Functor</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="w"> </span><span class="nf">operator</span><span class="p">()()</span><span class="w"> </span><span class="o">&</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="s">"L-val"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="w"> </span><span class="nf">operator</span><span class="p">()()</span><span class="w"> </span><span class="o">&&</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="s">"R-val"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">};</span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"-- copyable_function"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">mof1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="w"> </span><span class="o">&&></span><span class="w"> </span><span class="n">mof2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"mof1/L-val: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">mof1</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"mof1/R-val: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">mof1</span><span class="p">)()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="c1">//<a href="../iostream/cout.html">std::cout</a> << "mof2/L-val: " << mof2() << <a href="../ostream/endl.html">std::endl</a>; // 不適格</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"mof2/R-val: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">mof2</span><span class="p">)()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"-- function"</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="function.html">std::function</a></span><span class="o"><</span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">fn1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Functor</span><span class="p">{};</span>
<span class="c1">//<a href="function.html">std::function</a><<a href="../string/basic_string.html">std::string</a>(void) &&> fn2 = Functor{}; // 不適格</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"fn1/L-val: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">fn1</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"fn1/R-val: "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">fn1</span><span class="p">)()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</div></p>
<h4>出力</h4>
<p><pre><code>-- copyable_function
mof1/L-val: L-val
mof1/R-val: L-val
mof2/R-val: R-val
-- function
fn1/L-val: L-val
fn1/R-val: L-val
</code></pre></p>
<h3>例4: noexcept指定の伝搬</h3>
<p><div class="yata" id="3c2bbd5ac34569ea3e8ec47a4906800aa06de429"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../functional.html"><functional></a></span>
<span class="kt">void</span><span class="w"> </span><span class="nf">func</span><span class="p">()</span><span class="w"> </span><span class="p">{}</span>
<span class="kt">void</span><span class="w"> </span><span class="nf">func_noex</span><span class="p">()</span><span class="w"> </span><span class="k">noexcept</span><span class="w"> </span><span class="p">{}</span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="kt">void</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">mof1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">func</span><span class="p">;</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="kt">void</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">mof2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">func_noex</span><span class="p">;</span>
<span class="c1">//<span style="color:#ff0000">std::copyable_function</span><void(void) noexcept> mof3 = func; // 不適格</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">std::copyable_function</span></span><span class="o"><</span><span class="kt">void</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="w"> </span><span class="k">noexcept</span><span class="o">></span><span class="w"> </span><span class="n">mof4</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">func_noex</span><span class="p">;</span>
<span class="w"> </span><span class="k">static_assert</span><span class="p">(</span><span class="k">not</span><span class="w"> </span><span class="k">noexcept</span><span class="p">(</span><span class="n">mof1</span><span class="p">()));</span>
<span class="w"> </span><span class="k">static_assert</span><span class="p">(</span><span class="k">not</span><span class="w"> </span><span class="k">noexcept</span><span class="p">(</span><span class="n">mof2</span><span class="p">()));</span>
<span class="w"> </span><span class="k">static_assert</span><span class="p">(</span><span class="w"> </span><span class="k">noexcept</span><span class="p">(</span><span class="n">mof4</span><span class="p">()));</span>
<span class="w"> </span><span class="n"><a href="function.html">std::function</a></span><span class="o"><</span><span class="kt">void</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">fn1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">func</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="function.html">std::function</a></span><span class="o"><</span><span class="kt">void</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">fn2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">func_noex</span><span class="p">;</span>
<span class="c1">//<a href="function.html">std::function</a><void(void) noexcept> fn3 = func; // 不適格</span>
<span class="c1">//<a href="function.html">std::function</a><void(void) noexcept> fn4 = func_noex; // 不適格</span>
<span class="w"> </span><span class="k">static_assert</span><span class="p">(</span><span class="k">not</span><span class="w"> </span><span class="k">noexcept</span><span class="p">(</span><span class="n">fn1</span><span class="p">()));</span>
<span class="w"> </span><span class="k">static_assert</span><span class="p">(</span><span class="k">not</span><span class="w"> </span><span class="k">noexcept</span><span class="p">(</span><span class="n">fn2</span><span class="p">()));</span>
<span class="p">}</span>
</code></pre></div>
</div></p>
<h4>出力</h4>
<p><pre><code></code></pre></p>
<h2>バージョン</h2>
<h3>言語</h3>
<ul>
<li>C++26</li>
</ul>
<h3>処理系</h3>
<ul>
<li><a href="../../implementation.html#clang">Clang</a>: ??</li>
<li><a href="../../implementation.html#gcc">GCC</a>: ??</li>
<li><a href="../../implementation.html#icc">ICC</a>: ??</li>
<li><a href="../../implementation.html#visual_cpp">Visual C++</a>: ??</li>
</ul>
<h2>関連項目</h2>
<ul>
<li>C++11 <code><a href="function.html">function</a></code></li>
<li>C++23 <code><a href="move_only_function.html">move_only_function</a></code></li>
<li>C++26 <code><a href="function_ref.html">function_ref</a></code></li>
</ul>
<h2>参照</h2>
<ul>
<li><a href="https://open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2548r6.pdf" target="_blank">P2548R6 copyable_function</a></li>
</ul></div>
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