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  25. <div class="section">
  26. <div class="titlepage"><div><div><h3 class="title">
  27. <a name="boost_typetraits.reference.add_lvalue_reference"></a><a class="link" href="add_lvalue_reference.html" title="add_lvalue_reference">add_lvalue_reference</a>
  28. </h3></div></div></div>
  29. <pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  30. <span class="keyword">struct</span> <span class="identifier">add_lvalue_reference</span>
  31. <span class="special">{</span>
  32. <span class="keyword">typedef</span> <em class="replaceable"><code>see-below</code></em> <span class="identifier">type</span><span class="special">;</span>
  33. <span class="special">};</span>
  34. <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">using</span> <span class="identifier">add_lvalue_reference_t</span> <span class="special">=</span> <span class="keyword">typename</span> <span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">;</span> <span class="comment">// C++11 and above</span>
  35. </pre>
  36. <p>
  37. <span class="bold"><strong>type:</strong></span> If <code class="computeroutput"><span class="identifier">T</span></code>
  38. names an object or function type then the member typedef <code class="computeroutput"><span class="identifier">type</span></code>
  39. shall name <code class="computeroutput"><span class="identifier">T</span><span class="special">&amp;</span></code>;
  40. otherwise, if <code class="computeroutput"><span class="identifier">T</span></code> names a type
  41. <span class="emphasis"><em>rvalue reference to U</em></span> then the member typedef type shall
  42. name <code class="computeroutput"><span class="identifier">U</span><span class="special">&amp;</span></code>;
  43. otherwise, type shall name <code class="computeroutput"><span class="identifier">T</span></code>.
  44. </p>
  45. <p>
  46. <span class="bold"><strong>C++ Standard Reference:</strong></span> 20.7.6.2.
  47. </p>
  48. <p>
  49. <span class="bold"><strong>Header:</strong></span> <code class="computeroutput"> <span class="preprocessor">#include</span>
  50. <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">add_lvalue_reference</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
  51. or <code class="computeroutput"> <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
  52. </p>
  53. <div class="table">
  54. <a name="boost_typetraits.reference.add_lvalue_reference.examples"></a><p class="title"><b>Table&#160;1.12.&#160;Examples</b></p>
  55. <div class="table-contents"><table class="table" summary="Examples">
  56. <colgroup>
  57. <col>
  58. <col>
  59. </colgroup>
  60. <thead><tr>
  61. <th>
  62. <p>
  63. Expression
  64. </p>
  65. </th>
  66. <th>
  67. <p>
  68. Result Type
  69. </p>
  70. </th>
  71. </tr></thead>
  72. <tbody>
  73. <tr>
  74. <td>
  75. <p>
  76. <code class="computeroutput"><span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
  77. </p>
  78. </td>
  79. <td>
  80. <p>
  81. <code class="computeroutput"><span class="keyword">int</span><span class="special">&amp;</span></code>
  82. </p>
  83. </td>
  84. </tr>
  85. <tr>
  86. <td>
  87. <p>
  88. <code class="computeroutput"><span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="keyword">int</span>
  89. <span class="keyword">const</span><span class="special">&amp;&gt;::</span><span class="identifier">type</span></code>
  90. </p>
  91. </td>
  92. <td>
  93. <p>
  94. <code class="computeroutput"><span class="keyword">int</span> <span class="keyword">const</span><span class="special">&amp;</span></code>
  95. </p>
  96. </td>
  97. </tr>
  98. <tr>
  99. <td>
  100. <p>
  101. <code class="computeroutput"><span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">*&gt;::</span><span class="identifier">type</span></code>
  102. </p>
  103. </td>
  104. <td>
  105. <p>
  106. <code class="computeroutput"><span class="keyword">int</span><span class="special">*&amp;</span></code>
  107. </p>
  108. </td>
  109. </tr>
  110. <tr>
  111. <td>
  112. <p>
  113. <code class="computeroutput"><span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">*&amp;&gt;::</span><span class="identifier">type</span></code>
  114. </p>
  115. </td>
  116. <td>
  117. <p>
  118. <code class="computeroutput"><span class="keyword">int</span><span class="special">*&amp;</span></code>
  119. </p>
  120. </td>
  121. </tr>
  122. <tr>
  123. <td>
  124. <p>
  125. <code class="computeroutput"><span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&amp;&amp;&gt;::</span><span class="identifier">type</span></code>
  126. </p>
  127. </td>
  128. <td>
  129. <p>
  130. <code class="computeroutput"><span class="keyword">int</span><span class="special">&amp;</span></code>
  131. </p>
  132. </td>
  133. </tr>
  134. <tr>
  135. <td>
  136. <p>
  137. <code class="computeroutput"><span class="identifier">add_lvalue_reference</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
  138. </p>
  139. </td>
  140. <td>
  141. <p>
  142. <code class="computeroutput"><span class="keyword">void</span></code>
  143. </p>
  144. </td>
  145. </tr>
  146. </tbody>
  147. </table></div>
  148. </div>
  149. <br class="table-break"><p>
  150. <span class="bold"><strong>Compiler Compatibility:</strong></span> All current compilers
  151. are supported by this trait.
  152. </p>
  153. </div>
  154. <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
  155. <td align="left"></td>
  156. <td align="right"><div class="copyright-footer">Copyright &#169; 2000, 2011 Adobe Systems Inc, David Abrahams,
  157. Frederic Bron, Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant,
  158. Jesse Jones, Mat Marcus, Itay Maman, John Maddock, Alexander Nasonov, Thorsten
  159. Ottosen, Roman Perepelitsa, Robert Ramey, Jeremy Siek, Robert Stewart and Steven
  160. Watanabe<p>
  161. Distributed under the Boost Software License, Version 1.0. (See accompanying
  162. file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
  163. </p>
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