<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> <title>libsigc++: sigc::signal< T_return, T_arg1, T_arg2, T_arg3, T_arg4, T_arg5, T_arg6, T_arg7 >::accumulated< T_accumulator > Class Template Reference</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <link href="doxygen.css" rel="stylesheet" type="text/css"/> </head> <body> <!-- Generated by Doxygen 1.7.2 --> <div class="navigation" id="top"> <div class="tabs"> <ul class="tablist"> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="modules.html"><span>Modules</span></a></li> <li><a href="namespaces.html"><span>Namespaces</span></a></li> <li class="current"><a href="annotated.html"><span>Classes</span></a></li> </ul> </div> <div class="tabs2"> <ul class="tablist"> <li><a 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<p>Convenience wrapper for the numbered <a class="el" href="classsigc_1_1signal.html" title="Convenience wrapper for the numbered sigc::signal# templates.">sigc::signal</a># templates. <a href="#_details">More...</a></p> <p><code>#include <sigc++/signal.h></code></p> <!-- startSectionHeader --><div class="dynheader"> Inheritance diagram for sigc::signal< T_return, T_arg1, T_arg2, T_arg3, T_arg4, T_arg5, T_arg6, T_arg7 >::accumulated< T_accumulator >:<!-- endSectionHeader --></div> <!-- startSectionSummary --><!-- endSectionSummary --><!-- startSectionContent --><div class="dyncontent"> <div class="center"><img src="classsigc_1_1signal_1_1accumulated__inherit__graph.png" border="0" usemap="#sigc_1_1signal_3_01T__return_00_01T__arg1_00_01T__arg2_00_01T__arg3_00_01T__arg4_00_01T__arg5_00_01T__arg6_00_01T__arg7_01_4_1_1accumulated_3_01T__accumulator_01_4_inherit__map" alt="Inheritance graph"/></div> <map name="sigc_1_1signal_3_01T__return_00_01T__arg1_00_01T__arg2_00_01T__arg3_00_01T__arg4_00_01T__arg5_00_01T__arg6_00_01T__arg7_01_4_1_1accumulated_3_01T__accumulator_01_4_inherit__map" id="sigc_1_1signal_3_01T__return_00_01T__arg1_00_01T__arg2_00_01T__arg3_00_01T__arg4_00_01T__arg5_00_01T__arg6_00_01T__arg7_01_4_1_1accumulated_3_01T__accumulator_01_4_inherit__map"> <area shape="rect" id="node2" href="classsigc_1_1signal7.html" title="Signal declaration." alt="" coords="347,5,989,35"/><area shape="rect" id="node4" href="structsigc_1_1signal__base.html" title="Base class for the sigc::signal# templates." alt="" coords="168,5,299,35"/><area shape="rect" id="node6" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection." alt="" coords="5,5,120,35"/></map> <center><span class="legend">[<a href="graph_legend.html">legend</a>]</span></center><!-- endSectionContent --></div> <p><a href="classsigc_1_1signal_1_1accumulated-members.html">List of all members.</a></p> <table class="memberdecls"> <tr><td colspan="2"><h2><a name="pub-methods"></a> Public Member Functions</h2></td></tr> <tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a032428476a190d9dea6313f70e5b8a10"></a><!-- doxytag: member="sigc::signal::accumulated::accumulated" ref="a032428476a190d9dea6313f70e5b8a10" args="(const accumulated &src)" -->  </td><td class="memItemRight" valign="bottom"><b>accumulated</b> (const <a class="el" href="classsigc_1_1signal_1_1accumulated.html">accumulated</a>& src)</td></tr> </table> <hr/><a name="_details"></a><h2>Detailed Description</h2> <h3>template <class T_return, class T_arg1 = nil, class T_arg2 = nil, class T_arg3 = nil, class T_arg4 = nil, class T_arg5 = nil, class T_arg6 = nil, class T_arg7 = nil><br/> template <class T_accumulator><br/> class sigc::signal< T_return, T_arg1, T_arg2, T_arg3, T_arg4, T_arg5, T_arg6, T_arg7 >::accumulated< T_accumulator ></h3> <p>Convenience wrapper for the numbered <a class="el" href="classsigc_1_1signal.html" title="Convenience wrapper for the numbered sigc::signal# templates.">sigc::signal</a># templates. </p> <p>Like <a class="el" href="classsigc_1_1signal.html" title="Convenience wrapper for the numbered sigc::signal# templates.">sigc::signal</a> but the additional template parameter <em>T_accumulator</em> defines the accumulator type that should be used.</p> <p>An accumulator is a functor that uses a pair of special iterators to step through a list of slots and calculate a return value from the results of the slot invokations. The iterators' <a class="elRef" doxygen="libstdc++.tag:http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01164.html#ga02bdbe21b5a753599173b4e2c77b5497">operator*()</a> executes the slot. The return value is buffered, so that in an expression like </p> <div class="fragment"><pre class="fragment"> a = (*i) * (*i); </pre></div><p> the slot is executed only once. The accumulator must define its return value as <code>result_type</code>.</p> <dl class="user"><dt><b>Example 1:</b></dt><dd>This accumulator calculates the arithmetic mean value: <div class="fragment"><pre class="fragment"> <span class="keyword">struct </span>arithmetic_mean_accumulator { <span class="keyword">typedef</span> <span class="keywordtype">double</span> result_type; <span class="keyword">template</span><<span class="keyword">typename</span> T_iterator> result_type <a class="code" href="classsigc_1_1signal7.html#a11b73bd2c5d40e02eab78b38ce0d097d" title="Triggers the emission of the signal (see emit()).">operator()</a>(T_iterator first, T_iterator last)<span class="keyword"> const</span> <span class="keyword"> </span>{ result_type value_ = 0; <span class="keywordtype">int</span> n_ = 0; <span class="keywordflow">for</span> (; first != last; ++first, ++n_) value_ += *first; <span class="keywordflow">return</span> value_ / n_; } }; </pre></div></dd></dl> <dl class="user"><dt><b>Example 2:</b></dt><dd>This accumulator stops signal emission when a slot returns zero: <div class="fragment"><pre class="fragment"> <span class="keyword">struct </span>interruptable_accumulator { <span class="keyword">typedef</span> <span class="keywordtype">bool</span> result_type; <span class="keyword">template</span><<span class="keyword">typename</span> T_iterator> result_type <a class="code" href="classsigc_1_1signal7.html#a11b73bd2c5d40e02eab78b38ce0d097d" title="Triggers the emission of the signal (see emit()).">operator()</a>(T_iterator first, T_iterator last)<span class="keyword"> const</span> <span class="keyword"> </span>{ <span class="keywordflow">for</span> (; first != last; ++first, ++n_) <span class="keywordflow">if</span> (!*first) <span class="keywordflow">return</span> <span class="keyword">false</span>; <span class="keywordflow">return</span> <span class="keyword">true</span>; } }; </pre></div> </dd></dl> </div> <hr class="footer"/><address class="footer"><small>Generated on Tue Mar 8 2011 11:44:41 for libsigc++ by  <a href="http://www.doxygen.org/index.html"> <img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.7.2 </small></address> </body> </html>