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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="idm45555133055232"></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" style="list-style-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>
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<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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