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| <h2><span class="refentrytitle">Function template visit_each</span></h2> |
| <p>boost::visit_each — Allow limited exploration of class members.</p> |
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| <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="../signals/reference.html#header.boost.visit_each_hpp" title="Header <boost/visit_each.hpp>">boost/visit_each.hpp</a>> |
| |
| </span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Visitor<span class="special">,</span> <span class="keyword">typename</span> T<span class="special">></span> |
| <span class="keyword">void</span> <span class="identifier">visit_each</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">Visitor</span><span class="special">&</span> visitor<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> t<span class="special">,</span> <span class="keyword">int</span><span class="special">)</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2535553"></a><h2>Description</h2> |
| <p>The <code class="computeroutput"><a class="link" href="visit_each.html" title="Function template visit_each">visit_each</a></code> mechanism |
| allows a visitor to be applied to every subobject in a given |
| object. It is used by the Signals library to discover |
| <code class="computeroutput"><a class="link" href="signals/trackable.html" title="Class trackable">signals::trackable</a></code> objects within a |
| function object, but other uses may surface if used |
| universally (e.g., conservative garbage collection). To fit |
| within the <code class="computeroutput"><a class="link" href="visit_each.html" title="Function template visit_each">visit_each</a></code> framework, |
| a <code class="computeroutput"><a class="link" href="visit_each.html" title="Function template visit_each">visit_each</a></code> overload must be |
| supplied for each object type. </p> |
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| <td><p><span class="term">Effects:</span></p></td> |
| <td> |
| <p><code class="computeroutput">visitor(t)</code>, and for |
| every subobject <code class="computeroutput">x</code> of |
| <code class="computeroutput">t</code>: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"><p>If <code class="computeroutput">x</code> is a reference, <code class="computeroutput">visit_each(visitor, ref(x), 0)</code></p></li> |
| <li class="listitem"><p>Otherwise, <code class="computeroutput">visit_each(visitor, x, 0)</code></p></li> |
| </ul></div> |
| <p> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td><p><span class="term">Notes:</span></p></td> |
| <td> |
| <p>The third parameter is |
| <code class="computeroutput">long</code> for the fallback version |
| of <a class="link" href="visit_each.html" title="Function template visit_each">visit_each</a> and the argument |
| supplied to this third paramter must always be 0. The third |
| parameter is an artifact of the widespread lack of proper |
| function template ordering, and will be removed in the future.</p> |
| <p>Library authors will be expected to add additional |
| overloads that specialize the T argument for their classes, so |
| that subobjects can be visited.</p> |
| <p>Calls to visit_each are required to be unqualified, to |
| enable argument-dependent lookup.</p> |
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| <td align="right"><div class="copyright-footer">Copyright © 2001-2004 Douglas Gregor<p>Use, modification and distribution is 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> |
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