doc/html/boost/reference_wrapper.html


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<title>Class template reference_wrapper</title>
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<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 &#8212; 
        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: &lt;<a class="link" href="../ref/reference.html#header.boost.ref_hpp" title="Header &lt;boost/ref.hpp&gt;">boost/ref.hpp</a>&gt;

</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</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#id1302280-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>

  <span class="comment">// <a class="link" href="reference_wrapper.html#id1302311-bb">access</a></span>
  <a class="link" href="reference_wrapper.html#id1302314-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>
  <span class="identifier">T</span><span class="special">&amp;</span> <a class="link" href="reference_wrapper.html#id1302332-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#id1380104-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#id1380123-bb">constructors</a></span>
<span class="identifier">reference_wrapper</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <a class="link" href="reference_wrapper.html#boost.reference_wrapper.ref_id1380126"><span class="identifier">ref</span></a><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
<span class="identifier">reference_wrapper</span><span class="special">&lt;</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&gt;</span> <a class="link" href="reference_wrapper.html#boost.reference_wrapper.cref_id1380154"><span class="identifier">cref</span></a><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>

<span class="comment">// <a class="link" href="reference_wrapper.html#id1380183-bb">access</a></span>
<span class="identifier">unwrap_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span><span class="special">&amp;</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">&amp;</span><span class="special">)</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id3135768"></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&amp;</code>, which usually allows
        the function templates to work on references
        unmodified.</p>
<div class="refsect2">
<a name="id3135796"></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="id1302280-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>
<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="id3135897"></a><h3>
<a name="id1302311-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="id1302314-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>
<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">&amp;</span> <a name="id1302332-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="id1380104-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="id3136108"></a><h3>
<a name="id1380123-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">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <a name="boost.reference_wrapper.ref_id1380126"></a><span class="identifier">ref</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>
<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>&lt;T&gt;(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">&lt;</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&gt;</span> <a name="boost.reference_wrapper.cref_id1380154"></a><span class="identifier">cref</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</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>&lt;T const&gt;(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="id3136311"></a><h3>
<a name="id1380183-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">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span><span class="special">&amp;</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">&amp;</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>&lt;T&gt;::type&amp;(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 &#169; 1999, 2000 Jaakko J&#228;rvi<br>Copyright &#169; 2001, 2002 Peter Dimov<br>Copyright &#169; 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>
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