<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Class template reference_wrapper</title> <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../ref/reference.html#header.boost.ref_hpp" title="Header <boost/ref.hpp>"> <link rel="prev" href="../ref/reference.html" title="Reference"> <link rel="next" href="is_reference_wrapper.html" title="Class template is_reference_wrapper"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> <td align="center"><a href="../../../index.html">Home</a></td> <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="../ref/reference.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ref/reference.html#header.boost.ref_hpp"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="is_reference_wrapper.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="boost.reference_wrapper"></a><div class="titlepage"></div> <div class="refnamediv"> <h2><span class="refentrytitle">Class template reference_wrapper</span></h2> <p>boost::reference_wrapper — Contains a reference to an object of type <code class="computeroutput">T</code>. </p> </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../ref/reference.html#header.boost.ref_hpp" title="Header <boost/ref.hpp>">boost/ref.hpp</a>> </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <span class="keyword">class</span> <a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a> <span class="special">{</span> <span class="keyword">public</span><span class="special">:</span> <span class="comment">// types</span> <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> <span class="comment">// <a class="link" href="reference_wrapper.html#boost.reference_wrapperconstruct-copy-destruct">construct/copy/destruct</a></span> <span class="keyword">explicit</span> <a class="link" href="reference_wrapper.html#id1139003-bb"><span class="identifier">reference_wrapper</span></a><span class="special">(</span><span class="identifier">T</span><span class="special">&</span><span class="special">)</span><span class="special">;</span> <span class="comment">// <a class="link" href="reference_wrapper.html#id1139034-bb">access</a></span> <a class="link" href="reference_wrapper.html#id1139037-bb"><span class="keyword">operator</span> <span class="identifier">T</span><span class="special">&</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="identifier">T</span><span class="special">&</span> <a class="link" href="reference_wrapper.html#id1139054-bb"><span class="identifier">get</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="identifier">T</span><span class="special">*</span> <a class="link" href="reference_wrapper.html#id1139071-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> <span class="special">}</span><span class="special">;</span> <span class="comment">// <a class="link" href="reference_wrapper.html#id1139091-bb">constructors</a></span> <span class="identifier">reference_wrapper</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <a class="link" href="reference_wrapper.html#boost.reference_wrapper.ref_id1139095"><span class="identifier">ref</span></a><span class="special">(</span><span class="identifier">T</span><span class="special">&</span><span class="special">)</span><span class="special">;</span> <span class="identifier">reference_wrapper</span><span class="special"><</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">></span> <a class="link" href="reference_wrapper.html#boost.reference_wrapper.cref_id1139125"><span class="identifier">cref</span></a><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span><span class="special">)</span><span class="special">;</span> <span class="comment">// <a class="link" href="reference_wrapper.html#id1139156-bb">access</a></span> <span class="identifier">unwrap_reference</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span><span class="special">&</span> <a class="link" href="reference_wrapper.html#boost.reference_wrapper.unwrap_ref"><span class="identifier">unwrap_ref</span></a><span class="special">(</span><span class="identifier">T</span><span class="special">&</span><span class="special">)</span><span class="special">;</span></pre></div> <div class="refsect1"> <a name="id2533727"></a><h2>Description</h2> <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&</code>, which usually allows the function templates to work on references unmodified.</p> <div class="refsect2"> <a name="id2533754"></a><h3> <a name="boost.reference_wrapperconstruct-copy-destruct"></a><code class="computeroutput">reference_wrapper</code> public construct/copy/destruct</h3> <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> <pre class="literallayout"><span class="keyword">explicit</span> <a name="id1139003-bb"></a><span class="identifier">reference_wrapper</span><span class="special">(</span><span class="identifier">T</span><span class="special">&</span> t<span class="special">)</span><span class="special">;</span></pre> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Effects:</span></p></td> <td>Constructs a <code class="computeroutput"><a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a></code> object that stores a reference to <code class="computeroutput">t</code>.</td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li></ol></div> </div> <div class="refsect2"> <a name="id2534126"></a><h3> <a name="id1139034-bb"></a><code class="computeroutput">reference_wrapper</code> access</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><a name="id1139037-bb"></a><span class="keyword">operator</span> <span class="identifier">T</span><span class="special">&</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Returns:</span></p></td> <td>The stored reference.</td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><span class="identifier">T</span><span class="special">&</span> <a name="id1139054-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> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Returns:</span></p></td> <td>The stored reference.</td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><span class="identifier">T</span><span class="special">*</span> <a name="id1139071-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> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Returns:</span></p></td> <td>A pointer to the object referenced by the stored reference.</td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="id2534337"></a><h3> <a name="id1139091-bb"></a><code class="computeroutput">reference_wrapper</code> constructors</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><span class="identifier">reference_wrapper</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <a name="boost.reference_wrapper.ref_id1139095"></a><span class="identifier">ref</span><span class="special">(</span><span class="identifier">T</span><span class="special">&</span> t<span class="special">)</span><span class="special">;</span></pre> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Returns:</span></p></td> <td><code class="computeroutput"><a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a><T>(t)</code></td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><span class="identifier">reference_wrapper</span><span class="special"><</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">></span> <a name="boost.reference_wrapper.cref_id1139125"></a><span class="identifier">cref</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span> t<span class="special">)</span><span class="special">;</span></pre> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Returns:</span></p></td> <td><code class="computeroutput"><a class="link" href="reference_wrapper.html" title="Class template reference_wrapper">reference_wrapper</a><T const>(t)</code></td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li> </ol></div> </div> <div class="refsect2"> <a name="id2534540"></a><h3> <a name="id1139156-bb"></a><code class="computeroutput">reference_wrapper</code> access</h3> <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> <pre class="literallayout"><span class="identifier">unwrap_reference</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span><span class="special">&</span> <a name="boost.reference_wrapper.unwrap_ref"></a><span class="identifier">unwrap_ref</span><span class="special">(</span><span class="identifier">T</span><span class="special">&</span> t<span class="special">)</span><span class="special">;</span></pre> <div class="variablelist"><table border="0"> <col align="left" valign="top"> <tbody> <tr> <td><p><span class="term">Returns:</span></p></td> <td><code class="computeroutput"><a class="link" href="unwrap_reference.html" title="Class template unwrap_reference">unwrap_reference</a><T>::type&(t)</code></td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Does not throw.</td> </tr> </tbody> </table></div> </li></ol></div> </div> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 1999, 2000 Jaakko Järvi<br>Copyright © 2001, 2002 Peter Dimov<br>Copyright © 2002 David Abrahams<p>Subject to the Boost Software License, Version 1.0. See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>. </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="../ref/reference.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ref/reference.html#header.boost.ref_hpp"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="is_reference_wrapper.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>