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  48 <div class="title">Functors</div>  </div>
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  51
  52 <p>Functors are copyable types that define operator()().
  53 <a href="#details">More...</a></p>
  54 <table class="memberdecls">
  55 <tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="groups"></a>
  56 Modules</h2></td></tr>
  57 <tr class="memitem:group__slot"><td class="memItemLeft" align="right" valign="top">&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__slot.html">Slots</a></td></tr>
  58 <tr class="memdesc:group__slot"><td class="mdescLeft">&#160;</td><td class="mdescRight">Slots are type-safe representations of callback methods and functions. <br /></td></tr>
  59 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  60 <tr class="memitem:group__mem__fun"><td class="memItemLeft" align="right" valign="top">&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__mem__fun.html">mem_fun()</a></td></tr>
  61 <tr class="memdesc:group__mem__fun"><td class="mdescLeft">&#160;</td><td class="mdescRight"><a class="el" href="group__mem__fun.html#ga6ed5c519845b36eb7c6461ebd2a073c9" title="Creates a functor of type sigc::mem_functor which wraps a method. ">mem_fun()</a> is used to convert a pointer to a method to a functor. <br /></td></tr>
  62 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  63 <tr class="memitem:group__ptr__fun"><td class="memItemLeft" align="right" valign="top">&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__ptr__fun.html">ptr_fun()</a></td></tr>
  64 <tr class="memdesc:group__ptr__fun"><td class="mdescLeft">&#160;</td><td class="mdescRight"><a class="el" href="group__ptr__fun.html#ga203dd1ac5747cf2f3d2b2d590ad32e82" title="Creates a functor of type sigc::pointer_functor which wraps an existing non-member function...">ptr_fun()</a> is used to convert a pointer to a function to a functor. <br /></td></tr>
  65 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  66 </table><table class="memberdecls">
  67 <tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="nested-classes"></a>
  68 Classes</h2></td></tr>
  69 <tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classsigc_1_1can__deduce__result__type__with__decltype.html">sigc::can_deduce_result_type_with_decltype&lt; T_functor &gt;</a></td></tr>
  70 <tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Helper class, to determine if decltype() can deduce the result type of a functor.  <a href="classsigc_1_1can__deduce__result__type__with__decltype.html#details">More...</a><br /></td></tr>
  71 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  72 <tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structsigc_1_1functor__base.html">sigc::functor_base</a></td></tr>
  73 <tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">A hint to the compiler.  <a href="structsigc_1_1functor__base.html#details">More...</a><br /></td></tr>
  74 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  75 <tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structsigc_1_1functor__trait.html">sigc::functor_trait&lt; T_functor, I_derives_functor_base, I_can_use_decltype &gt;</a></td></tr>
  76 <tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Trait that specifies the return type of any type.  <a href="structsigc_1_1functor__trait.html#details">More...</a><br /></td></tr>
  77 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  78 <tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structsigc_1_1visitor.html">sigc::visitor&lt; T_functor &gt;</a></td></tr>
  79 <tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight"><a class="el" href="structsigc_1_1visitor.html#a9fe5d6be845e622a99a0db5d3621d4b3">sigc::visitor&lt;T_functor&gt;::do_visit_each()</a> performs a functor on each of the targets of a functor.  <a href="structsigc_1_1visitor.html#details">More...</a><br /></td></tr>
  80 <tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
  81 </table><table class="memberdecls">
  82 <tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="define-members"></a>
  83 Macros</h2></td></tr>
  84 <tr class="memitem:ga7a6f5575dc0b0ea896889c782721f6be"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__sigcfunctors.html#ga7a6f5575dc0b0ea896889c782721f6be">SIGC_FUNCTOR_TRAIT</a>(T_functor,  T_return)</td></tr>
  85 <tr class="memdesc:ga7a6f5575dc0b0ea896889c782721f6be"><td class="mdescLeft">&#160;</td><td class="mdescRight">Helper macro, if you want to mix user-defined and third party functors with libsigc++.  <a href="#ga7a6f5575dc0b0ea896889c782721f6be">More...</a><br /></td></tr>
  86 <tr class="separator:ga7a6f5575dc0b0ea896889c782721f6be"><td class="memSeparator" colspan="2">&#160;</td></tr>
  87 <tr class="memitem:gadf1ba3cacb09cc5c3c3e399836ec6e50"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__sigcfunctors.html#gadf1ba3cacb09cc5c3c3e399836ec6e50">SIGC_FUNCTORS_DEDUCE_RESULT_TYPE_WITH_DECLTYPE</a></td></tr>
  88 <tr class="memdesc:gadf1ba3cacb09cc5c3c3e399836ec6e50"><td class="mdescLeft">&#160;</td><td class="mdescRight">Helper macro, if you want to mix user-defined and third party functors with libsigc++.  <a href="#gadf1ba3cacb09cc5c3c3e399836ec6e50">More...</a><br /></td></tr>
  89 <tr class="separator:gadf1ba3cacb09cc5c3c3e399836ec6e50"><td class="memSeparator" colspan="2">&#160;</td></tr>
  90 <tr class="memitem:ga93b6ee8815d90adccfdceed72bcda577"><td class="memItemLeft" align="right" valign="top">#define&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__sigcfunctors.html#ga93b6ee8815d90adccfdceed72bcda577">SIGC_FUNCTORS_HAVE_RESULT_TYPE</a></td></tr>
  91 <tr class="memdesc:ga93b6ee8815d90adccfdceed72bcda577"><td class="mdescLeft">&#160;</td><td class="mdescRight">Helper macro, if you want to mix user-defined and third party functors with libsigc++.  <a href="#ga93b6ee8815d90adccfdceed72bcda577">More...</a><br /></td></tr>
  92 <tr class="separator:ga93b6ee8815d90adccfdceed72bcda577"><td class="memSeparator" colspan="2">&#160;</td></tr>
  93 </table><table class="memberdecls">
  94 <tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
  95 Functions</h2></td></tr>
  96 <tr class="memitem:ga64cb7832acc1e58efb5ffe0b4f5e9404"><td class="memTemplParams" colspan="2">template&lt;class T_action , class T_functor &gt; </td></tr>
  97 <tr class="memitem:ga64cb7832acc1e58efb5ffe0b4f5e9404"><td class="memTemplItemLeft" align="right" valign="top">void&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="group__sigcfunctors.html#ga64cb7832acc1e58efb5ffe0b4f5e9404">sigc::visit_each</a> (const T_action&amp; _A_action, const T_functor&amp; _A_functor)</td></tr>
  98 <tr class="memdesc:ga64cb7832acc1e58efb5ffe0b4f5e9404"><td class="mdescLeft">&#160;</td><td class="mdescRight">This function performs a functor on each of the targets of a functor.  <a href="#ga64cb7832acc1e58efb5ffe0b4f5e9404">More...</a><br /></td></tr>
  99 <tr class="separator:ga64cb7832acc1e58efb5ffe0b4f5e9404"><td class="memSeparator" colspan="2">&#160;</td></tr>
 100 <tr class="memitem:gada222d975b87d64cfa7a7f29244ae587"><td class="memTemplParams" colspan="2">template&lt;class T_type , class T_action , class T_functor &gt; </td></tr>
 101 <tr class="memitem:gada222d975b87d64cfa7a7f29244ae587"><td class="memTemplItemLeft" align="right" valign="top">void&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="group__sigcfunctors.html#gada222d975b87d64cfa7a7f29244ae587">sigc::visit_each_type</a> (const T_action&amp; _A_action, const T_functor&amp; _A_functor)</td></tr>
 102 <tr class="memdesc:gada222d975b87d64cfa7a7f29244ae587"><td class="mdescLeft">&#160;</td><td class="mdescRight">This function performs a functor on each of the targets of a functor limited to a restricted type.  <a href="#gada222d975b87d64cfa7a7f29244ae587">More...</a><br /></td></tr>
 103 <tr class="separator:gada222d975b87d64cfa7a7f29244ae587"><td class="memSeparator" colspan="2">&#160;</td></tr>
 104 </table>
 105 <a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
 106 <p>Functors are copyable types that define operator()(). </p>
 107 <p>Types that define operator()() overloads with different return types are referred to as multi-type functors. Multi-type functors are only partially supported in libsigc++.</p>
 108 <p>Closures are functors that store all information needed to invoke a callback from operator()().</p>
 109 <p>Adaptors are functors that alter the signature of a functor's operator()().</p>
 110 <p>libsigc++ defines numerous functors, closures and adaptors. Since libsigc++ is a callback library, most functors are also closures. The documentation doesn't distinguish between functors and closures.</p>
 111 <p>The basic functor types libsigc++ provides are created with <a class="el" href="group__ptr__fun.html#ga203dd1ac5747cf2f3d2b2d590ad32e82" title="Creates a functor of type sigc::pointer_functor which wraps an existing non-member function...">ptr_fun()</a> and <a class="el" href="group__mem__fun.html#ga6ed5c519845b36eb7c6461ebd2a073c9" title="Creates a functor of type sigc::mem_functor which wraps a method. ">mem_fun()</a> and can be converted into slots implicitly. The set of adaptors that ships with libsigc++ is documented in the <a class="el" href="group__adaptors.html">Adaptors</a> module.</p>
 112 <p>If you want to mix user-defined and third party functors with libsigc++, and you want them to be implicitly convertible into slots, libsigc++ must know the result type of your functors. There are different ways to achieve that.</p>
 113 <ul>
 114 <li>Derive your functors from <a class="el" href="structsigc_1_1functor__base.html" title="A hint to the compiler. ">sigc::functor_base</a> and place <code>using result_type = T_return;</code> in the class definition.</li>
 115 <li>Use the macro <a class="el" href="group__sigcfunctors.html#ga7a6f5575dc0b0ea896889c782721f6be" title="Helper macro, if you want to mix user-defined and third party functors with libsigc++. ">SIGC_FUNCTOR_TRAIT(T_functor,T_return)</a> in namespace sigc. Multi-type functors are only partly supported.</li>
 116 <li>For functors not derived from <a class="el" href="structsigc_1_1functor__base.html" title="A hint to the compiler. ">sigc::functor_base</a>, and not specified with <a class="el" href="group__sigcfunctors.html#ga7a6f5575dc0b0ea896889c782721f6be" title="Helper macro, if you want to mix user-defined and third party functors with libsigc++. ">SIGC_FUNCTOR_TRAIT()</a>, libsigc++ tries to deduce the result type with the C++11 decltype() specifier. That attempt usually succeeds if the functor has a single operator()(), but it fails if operator()() is overloaded.</li>
 117 <li>Use the macro <a class="el" href="group__sigcfunctors.html#ga93b6ee8815d90adccfdceed72bcda577" title="Helper macro, if you want to mix user-defined and third party functors with libsigc++. ">SIGC_FUNCTORS_HAVE_RESULT_TYPE</a>, if you want libsigc++ to assume that result_type is defined in all user-defined or third party functors, whose result type can't be deduced in any other way.</li>
 118 </ul>
 119 <p>If all these ways to deduce the result type fail, void is assumed.</p>
 120 <p>With libsigc++ versions before 2.6, the macro <a class="el" href="group__sigcfunctors.html#gadf1ba3cacb09cc5c3c3e399836ec6e50" title="Helper macro, if you want to mix user-defined and third party functors with libsigc++. ">SIGC_FUNCTORS_DEDUCE_RESULT_TYPE_WITH_DECLTYPE</a> activated the test with decltype(). That macro is now unneccesary and deprecated. </p>
 121 <h2 class="groupheader">Macro Definition Documentation</h2>
 122 <a class="anchor" id="ga7a6f5575dc0b0ea896889c782721f6be"></a>
 123 <div class="memitem">
 124 <div class="memproto">
 125       <table class="memname">
 126         <tr>
 127           <td class="memname">#define SIGC_FUNCTOR_TRAIT</td>
 128           <td>(</td>
 129           <td class="paramtype">&#160;</td>
 130           <td class="paramname">T_functor, </td>
 131         </tr>
 132         <tr>
 133           <td class="paramkey"></td>
 134           <td></td>
 135           <td class="paramtype">&#160;</td>
 136           <td class="paramname">T_return&#160;</td>
 137         </tr>
 138         <tr>
 139           <td></td>
 140           <td>)</td>
 141           <td></td><td></td>
 142         </tr>
 143       </table>
 144 </div><div class="memdoc">
 145
 146 <p>Helper macro, if you want to mix user-defined and third party functors with libsigc++. </p>
 147 <p>If you want to mix functors not derived from <a class="el" href="structsigc_1_1functor__base.html" title="A hint to the compiler. ">sigc::functor_base</a> with libsigc++, and these functors don't define <code>result_type</code>, use this macro inside namespace sigc to expose the return type of the functors like so: </p><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;namespace sigc {</div>
 148 <div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;  SIGC_FUNCTOR_TRAIT(first_functor_type, return_type_of_first_functor_type)</div>
 149 <div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;  SIGC_FUNCTOR_TRAIT(second_functor_type, return_type_of_second_functor_type)</div>
 150 <div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;  ...</div>
 151 <div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;}</div>
 152 </div><!-- fragment -->
 153 </div>
 154 </div>
 155 <a class="anchor" id="gadf1ba3cacb09cc5c3c3e399836ec6e50"></a>
 156 <div class="memitem">
 157 <div class="memproto">
 158       <table class="memname">
 159         <tr>
 160           <td class="memname">#define SIGC_FUNCTORS_DEDUCE_RESULT_TYPE_WITH_DECLTYPE</td>
 161         </tr>
 162       </table>
 163 </div><div class="memdoc">
 164
 165 <p>Helper macro, if you want to mix user-defined and third party functors with libsigc++. </p>
 166 <p>If you want to mix functors not derived from <a class="el" href="structsigc_1_1functor__base.html" title="A hint to the compiler. ">sigc::functor_base</a> with libsigc++, and your compiler can deduce the result type of the functor with the C++11 keyword <code>decltype</code>, use this macro inside namespace sigc like so: </p><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;namespace sigc {</div>
 167 <div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;  SIGC_FUNCTORS_DEDUCE_RESULT_TYPE_WITH_DECLTYPE</div>
 168 <div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;}</div>
 169 </div><!-- fragment --><p>Functors with overloaded operator()() are not supported.</p>
 170 <dl class="since_2_2_11"><dt><b><a class="el" href="since_2_2_11.html#_since_2_2_11000001">Since libsigc++ 2.2.11:</a></b></dt><dd></dd></dl>
 171 <dl class="deprecated"><dt><b><a class="el" href="deprecated.html#_deprecated000001">Deprecated:</a></b></dt><dd>This macro does nothing. The test it activated in libsigc++ versions before 2.6, is now unconditionally activated.</dd></dl>
 172
 173 </div>
 174 </div>
 175 <a class="anchor" id="ga93b6ee8815d90adccfdceed72bcda577"></a>
 176 <div class="memitem">
 177 <div class="memproto">
 178       <table class="memname">
 179         <tr>
 180           <td class="memname">#define SIGC_FUNCTORS_HAVE_RESULT_TYPE</td>
 181         </tr>
 182       </table>
 183 </div><div class="memdoc">
 184
 185 <p>Helper macro, if you want to mix user-defined and third party functors with libsigc++. </p>
 186 <p>If you want to mix functors not derived from <a class="el" href="structsigc_1_1functor__base.html" title="A hint to the compiler. ">sigc::functor_base</a> with libsigc++, and these functors define <code>result_type</code>, use this macro inside namespace sigc like so: </p><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;namespace sigc { SIGC_FUNCTORS_HAVE_RESULT_TYPE }</div>
 187 </div><!-- fragment -->
 188 </div>
 189 </div>
 190 <h2 class="groupheader">Function Documentation</h2>
 191 <a class="anchor" id="ga64cb7832acc1e58efb5ffe0b4f5e9404"></a>
 192 <div class="memitem">
 193 <div class="memproto">
 194 <div class="memtemplate">
 195 template &lt;class T_action , class T_functor &gt; </div>
 196       <table class="memname">
 197         <tr>
 198           <td class="memname">void sigc::visit_each </td>
 199           <td>(</td>
 200           <td class="paramtype">const T_action &amp;&#160;</td>
 201           <td class="paramname"><em>_A_action</em>, </td>
 202         </tr>
 203         <tr>
 204           <td class="paramkey"></td>
 205           <td></td>
 206           <td class="paramtype">const T_functor &amp;&#160;</td>
 207           <td class="paramname"><em>_A_functor</em>&#160;</td>
 208         </tr>
 209         <tr>
 210           <td></td>
 211           <td>)</td>
 212           <td></td><td></td>
 213         </tr>
 214       </table>
 215 </div><div class="memdoc">
 216
 217 <p>This function performs a functor on each of the targets of a functor. </p>
 218
 219 </div>
 220 </div>
 221 <a class="anchor" id="gada222d975b87d64cfa7a7f29244ae587"></a>
 222 <div class="memitem">
 223 <div class="memproto">
 224 <div class="memtemplate">
 225 template &lt;class T_type , class T_action , class T_functor &gt; </div>
 226       <table class="memname">
 227         <tr>
 228           <td class="memname">void sigc::visit_each_type </td>
 229           <td>(</td>
 230           <td class="paramtype">const T_action &amp;&#160;</td>
 231           <td class="paramname"><em>_A_action</em>, </td>
 232         </tr>
 233         <tr>
 234           <td class="paramkey"></td>
 235           <td></td>
 236           <td class="paramtype">const T_functor &amp;&#160;</td>
 237           <td class="paramname"><em>_A_functor</em>&#160;</td>
 238         </tr>
 239         <tr>
 240           <td></td>
 241           <td>)</td>
 242           <td></td><td></td>
 243         </tr>
 244       </table>
 245 </div><div class="memdoc">
 246
 247 <p>This function performs a functor on each of the targets of a functor limited to a restricted type. </p>
 248
 249 </div>
 250 </div>
 251 </div><!-- contents -->
 252 <!-- start footer part -->
 253 <hr class="footer"/><address class="footer"><small>
 254 Generated on Wed Mar 16 2016 20:53:27 for libsigc++ by &#160;<a href="http://www.doxygen.org/index.html">
 255 <img class="footer" src="doxygen.png" alt="doxygen"/>
 256 </a> 1.8.9.1
 257 </small></address>
 258 </body>
 259 </html>