reference_wrapper.html 11 KB

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  1. <html>
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  4. <title>Class template reference_wrapper</title>
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  24. </div>
  25. <div class="refentry">
  26. <a name="boost.reference_wrapper"></a><div class="titlepage"></div>
  27. <div class="refnamediv">
  28. <h2><span class="refentrytitle">Class template reference_wrapper</span></h2>
  29. <p>boost::reference_wrapper &#8212; Contains a reference to an object of type <code class="computeroutput">T</code>. </p>
  30. </div>
  31. <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32. <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../core/ref.html#header.boost.core.ref_hpp" title="Header &lt;boost/core/ref.hpp&gt;">boost/core/ref.hpp</a>&gt;
  33. </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  34. <span class="keyword">class</span> <a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a> <span class="special">{</span>
  35. <span class="keyword">public</span><span class="special">:</span>
  36. <span class="comment">// <a class="link" href="reference_wrapper.html#boost.reference_wrappertypes">types</a></span>
  37. <span class="keyword">typedef</span> <span class="identifier">T</span> <a class="link" href="reference_wrapper.html#boost.reference_wrapper.type"><span class="identifier">type</span></a><span class="special">;</span>
  38. <span class="comment">// <a class="link" href="reference_wrapper.html#boost.reference_wrapperconstruct-copy-destruct">construct/copy/destruct</a></span>
  39. <span class="keyword">explicit</span> <a class="link" href="reference_wrapper.html#idm45818739695344-bb"><span class="identifier">reference_wrapper</span></a><span class="special">(</span><span class="identifier">T</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  40. <a class="link" href="reference_wrapper.html#idm45818739691824-bb"><span class="identifier">reference_wrapper</span></a><span class="special">(</span><span class="identifier">T</span> <span class="special">&amp;&amp;</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  41. <span class="comment">// <a class="link" href="reference_wrapper.html#idm45818732268720-bb">public member functions</a></span>
  42. <a class="link" href="reference_wrapper.html#idm45818732268160-bb"><span class="keyword">operator</span> <span class="identifier">T</span> <span class="special">&amp;</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  43. <span class="identifier">T</span> <span class="special">&amp;</span> <a class="link" href="reference_wrapper.html#idm45818732265600-bb"><span class="identifier">get</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  44. <span class="identifier">T</span> <span class="special">*</span> <a class="link" href="reference_wrapper.html#idm45818739698032-bb"><span class="identifier">get_pointer</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  45. <span class="special">}</span><span class="special">;</span></pre></div>
  46. <div class="refsect1">
  47. <a name="idm46687073625248"></a><h2>Description</h2>
  48. <p><code class="computeroutput"><a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a></code> is primarily used to "feed" references to function templates (algorithms) that take their parameter by value. It provides an implicit conversion to <code class="computeroutput">T&amp;</code>, which usually allows the function templates to work on references unmodified. </p>
  49. <div class="refsect2">
  50. <a name="idm46687073622656"></a><h3>
  51. <a name="boost.reference_wrappertypes"></a><code class="computeroutput">reference_wrapper</code>
  52. public
  53. types</h3>
  54. <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
  55. <p>
  56. <span class="keyword">typedef</span> <span class="identifier">T</span> <a name="boost.reference_wrapper.type"></a><span class="identifier">type</span><span class="special">;</span></p>
  57. <p>Type <code class="computeroutput">T</code>. </p>
  58. </li></ol></div>
  59. </div>
  60. <div class="refsect2">
  61. <a name="idm46687073616064"></a><h3>
  62. <a name="boost.reference_wrapperconstruct-copy-destruct"></a><code class="computeroutput">reference_wrapper</code>
  63. public
  64. construct/copy/destruct</h3>
  65. <div class="orderedlist"><ol class="orderedlist" type="1">
  66. <li class="listitem">
  67. <pre class="literallayout"><span class="keyword">explicit</span> <a name="idm45818739695344-bb"></a><span class="identifier">reference_wrapper</span><span class="special">(</span><span class="identifier">T</span> <span class="special">&amp;</span> t<span class="special">)</span><span class="special">;</span></pre>
  68. <p>Constructs a <code class="computeroutput"><code class="computeroutput"><a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a></code></code> object that stores a reference to <code class="computeroutput">t</code>.</p>
  69. <p>Does not throw. </p>
  70. <p>
  71. </p>
  72. </li>
  73. <li class="listitem">
  74. <pre class="literallayout"><a name="idm45818739691824-bb"></a><span class="identifier">reference_wrapper</span><span class="special">(</span><span class="identifier">T</span> <span class="special">&amp;&amp;</span> t<span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span></pre>
  75. <p>Construction from a temporary object is disabled. </p>
  76. <p>
  77. </p>
  78. </li>
  79. </ol></div>
  80. </div>
  81. <div class="refsect2">
  82. <a name="idm46687073598192"></a><h3>
  83. <a name="idm45818732268720-bb"></a><code class="computeroutput">reference_wrapper</code> public member functions</h3>
  84. <div class="orderedlist"><ol class="orderedlist" type="1">
  85. <li class="listitem">
  86. <pre class="literallayout"><a name="idm45818732268160-bb"></a><span class="keyword">operator</span> <span class="identifier">T</span> <span class="special">&amp;</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
  87. <p>
  88. </p>
  89. <p>Does not throw. </p>
  90. <p>
  91. </p>
  92. <div class="variablelist"><table border="0" class="variablelist compact">
  93. <colgroup>
  94. <col align="left" valign="top">
  95. <col>
  96. </colgroup>
  97. <tbody><tr>
  98. <td><p><span class="term">Returns:</span></p></td>
  99. <td><p>The stored reference. </p></td>
  100. </tr></tbody>
  101. </table></div>
  102. </li>
  103. <li class="listitem">
  104. <pre class="literallayout"><span class="identifier">T</span> <span class="special">&amp;</span> <a name="idm45818732265600-bb"></a><span class="identifier">get</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
  105. <p>
  106. </p>
  107. <p>Does not throw. </p>
  108. <p>
  109. </p>
  110. <div class="variablelist"><table border="0" class="variablelist compact">
  111. <colgroup>
  112. <col align="left" valign="top">
  113. <col>
  114. </colgroup>
  115. <tbody><tr>
  116. <td><p><span class="term">Returns:</span></p></td>
  117. <td><p>The stored reference. </p></td>
  118. </tr></tbody>
  119. </table></div>
  120. </li>
  121. <li class="listitem">
  122. <pre class="literallayout"><span class="identifier">T</span> <span class="special">*</span> <a name="idm45818739698032-bb"></a><span class="identifier">get_pointer</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
  123. <p>
  124. </p>
  125. <p>Does not throw. </p>
  126. <p>
  127. </p>
  128. <div class="variablelist"><table border="0" class="variablelist compact">
  129. <colgroup>
  130. <col align="left" valign="top">
  131. <col>
  132. </colgroup>
  133. <tbody><tr>
  134. <td><p><span class="term">Returns:</span></p></td>
  135. <td><p>A pointer to the object referenced by the stored reference. </p></td>
  136. </tr></tbody>
  137. </table></div>
  138. </li>
  139. </ol></div>
  140. </div>
  141. </div>
  142. </div>
  143. <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
  144. <td align="left"></td>
  145. <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Peter Dimov<br>Copyright &#169; 2014 Glen Fernandes<br>Copyright &#169; 2014 Andrey Semashev<p>
  146. Distributed under the <a href="http://boost.org/LICENSE_1_0.txt" target="_top">Boost
  147. Software License, Version 1.0</a>.
  148. </p>
  149. </div></td>
  150. </tr></table>
  151. <hr>
  152. <div class="spirit-nav">
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