<!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::const_limit_reference< T_type, I_derives_trackable > 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 href="annotated.html"><span>Class List</span></a></li> <li><a href="classes.html"><span>Class Index</span></a></li> <li><a href="hierarchy.html"><span>Class Hierarchy</span></a></li> <li><a href="functions.html"><span>Class Members</span></a></li> </ul> </div> <div class="navpath"> <ul> <li><a class="el" href="namespacesigc.html">sigc</a> </li> <li><a class="el" href="classsigc_1_1const__limit__reference.html">const_limit_reference</a> </li> </ul> </div> </div> <div class="header"> <div class="summary"> <a href="#pub-methods">Public Member Functions</a> </div> <div class="headertitle"> <h1>sigc::const_limit_reference< T_type, I_derives_trackable > Class Template Reference</h1> </div> </div> <div class="contents"> <!-- doxytag: class="sigc::const_limit_reference" --> <p>A const_limit_reference<Foo> object stores a reference (Foo&), but make sure that, if Foo inherits from <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a>, then <a class="el" href="group__sigcfunctors.html#gadab29aed05524743da16319da4430541" title="This function performs a functor on each of the targets of a functor.">visit_each<>()</a> will "limit" itself to the <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a> reference instead of the derived reference. <a href="#_details">More...</a></p> <p><code>#include <sigc++/limit_reference.h></code></p> <p><a href="classsigc_1_1const__limit__reference-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"> </td><td class="memItemRight" valign="bottom"><a class="el" href="classsigc_1_1const__limit__reference.html#acee8a4c09720730cd5f66696fd018b4c">const_limit_reference</a> (const T_type& _A_target)</td></tr> <tr><td class="mdescLeft"> </td><td class="mdescRight">Constructor. <a href="#acee8a4c09720730cd5f66696fd018b4c"></a><br/></td></tr> <tr><td class="memItemLeft" align="right" valign="top">const T_type& </td><td class="memItemRight" valign="bottom"><a class="el" href="classsigc_1_1const__limit__reference.html#a9518c78a342f7d4bba9ca01b129c894d">visit</a> () const </td></tr> <tr><td class="mdescLeft"> </td><td class="mdescRight">Retrieve the entity to visit for <a class="el" href="group__sigcfunctors.html#gadab29aed05524743da16319da4430541" title="This function performs a functor on each of the targets of a functor.">visit_each()</a>. <a href="#a9518c78a342f7d4bba9ca01b129c894d"></a><br/></td></tr> <tr><td class="memItemLeft" align="right" valign="top">const T_type& </td><td class="memItemRight" valign="bottom"><a class="el" href="classsigc_1_1const__limit__reference.html#a2cb583845b99f2fdb56297bc6dff57d0">invoke</a> () const </td></tr> <tr><td class="mdescLeft"> </td><td class="mdescRight">Retrieve the reference. <a href="#a2cb583845b99f2fdb56297bc6dff57d0"></a><br/></td></tr> </table> <hr/><a name="_details"></a><h2>Detailed Description</h2> <h3>template <class T_type, bool I_derives_trackable = is_base_and_derived<trackable, T_type>::value><br/> class sigc::const_limit_reference< T_type, I_derives_trackable ></h3> <p>A const_limit_reference<Foo> object stores a reference (Foo&), but make sure that, if Foo inherits from <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a>, then <a class="el" href="group__sigcfunctors.html#gadab29aed05524743da16319da4430541" title="This function performs a functor on each of the targets of a functor.">visit_each<>()</a> will "limit" itself to the <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a> reference instead of the derived reference. </p> <p>This avoids use of a reference to the derived type when the derived destructor has run. That can be a problem when using virtual inheritance.</p> <p>If Foo inherits from trackable then both the derived reference and the <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a> reference are stored, so we can later retrieve the <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a> reference without doing an implicit conversion. To retrieve the derived reference (so that you invoke methods or members of it), use <a class="el" href="classsigc_1_1const__limit__reference.html#a2cb583845b99f2fdb56297bc6dff57d0" title="Retrieve the reference.">invoke()</a>. To retrieve the trackable reference (so that you can call <a class="el" href="group__sigcfunctors.html#gadab29aed05524743da16319da4430541" title="This function performs a functor on each of the targets of a functor.">visit_each()</a> on it), you use <a class="el" href="classsigc_1_1const__limit__reference.html#a9518c78a342f7d4bba9ca01b129c894d" title="Retrieve the entity to visit for visit_each().">visit()</a>.</p> <p>If Foo does not inherit from <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a> then <a class="el" href="classsigc_1_1const__limit__reference.html#a2cb583845b99f2fdb56297bc6dff57d0" title="Retrieve the reference.">invoke()</a> and <a class="el" href="classsigc_1_1const__limit__reference.html#a9518c78a342f7d4bba9ca01b129c894d" title="Retrieve the entity to visit for visit_each().">visit()</a> just return the derived reference.</p> <p>This is used for bound (sigc::bind) slot parameters (via <a class="el" href="classsigc_1_1bound__argument.html" title="A bound_argument<Foo> object stores a bound (for instance, with sigc::bind(), or sigc::bind_return()) argument.">bound_argument</a>), bound return values, and, with <a class="elRef" doxygen="libstdc++.tag:http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01197.html#ga58aa3b67eba2b8219e7aec7d4cdebcdb">mem_fun()</a>, the reference to the handling object.</p> <ul> <li><em>T_type</em> The type of the reference. </li> </ul> <hr/><h2>Constructor & Destructor Documentation</h2> <a class="anchor" id="acee8a4c09720730cd5f66696fd018b4c"></a><!-- doxytag: member="sigc::const_limit_reference::const_limit_reference" ref="acee8a4c09720730cd5f66696fd018b4c" args="(const T_type &_A_target)" --> <div class="memitem"> <div class="memproto"> <div class="memtemplate"> template <class T_type, bool I_derives_trackable = is_base_and_derived<trackable, T_type>::value> </div> <table class="memname"> <tr> <td class="memname"><a class="el" href="classsigc_1_1const__limit__reference.html">sigc::const_limit_reference</a>< T_type, I_derives_trackable >::<a class="el" href="classsigc_1_1const__limit__reference.html">const_limit_reference</a> </td> <td>(</td> <td class="paramtype">const T_type & </td> <td class="paramname"> <em>_A_target</em> )</td> <td><code> [inline]</code></td> </tr> </table> </div> <div class="memdoc"> <p>Constructor. </p> <dl><dt><b>Parameters:</b></dt><dd> <table class="params"> <tr><td class="paramname">_A_target</td><td>The reference to limit. </td></tr> </table> </dd> </dl> </div> </div> <hr/><h2>Member Function Documentation</h2> <a class="anchor" id="a2cb583845b99f2fdb56297bc6dff57d0"></a><!-- doxytag: member="sigc::const_limit_reference::invoke" ref="a2cb583845b99f2fdb56297bc6dff57d0" args="() const " --> <div class="memitem"> <div class="memproto"> <div class="memtemplate"> template <class T_type, bool I_derives_trackable = is_base_and_derived<trackable, T_type>::value> </div> <table class="memname"> <tr> <td class="memname">const T_type& <a class="el" href="classsigc_1_1const__limit__reference.html">sigc::const_limit_reference</a>< T_type, I_derives_trackable >::invoke </td> <td>(</td> <td class="paramname"> )</td> <td> const<code> [inline]</code></td> </tr> </table> </div> <div class="memdoc"> <p>Retrieve the reference. </p> <p>This is always a reference to the derived instance. </p> <dl class="return"><dt><b>Returns:</b></dt><dd>The reference. </dd></dl> </div> </div> <a class="anchor" id="a9518c78a342f7d4bba9ca01b129c894d"></a><!-- doxytag: member="sigc::const_limit_reference::visit" ref="a9518c78a342f7d4bba9ca01b129c894d" args="() const " --> <div class="memitem"> <div class="memproto"> <div class="memtemplate"> template <class T_type, bool I_derives_trackable = is_base_and_derived<trackable, T_type>::value> </div> <table class="memname"> <tr> <td class="memname">const T_type& <a class="el" href="classsigc_1_1const__limit__reference.html">sigc::const_limit_reference</a>< T_type, I_derives_trackable >::visit </td> <td>(</td> <td class="paramname"> )</td> <td> const<code> [inline]</code></td> </tr> </table> </div> <div class="memdoc"> <p>Retrieve the entity to visit for <a class="el" href="group__sigcfunctors.html#gadab29aed05524743da16319da4430541" title="This function performs a functor on each of the targets of a functor.">visit_each()</a>. </p> <p>Depending on the template specialization, this is either a derived reference, or <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a>& if T_type derives from <a class="el" href="structsigc_1_1trackable.html" title="Base class for objects with auto-disconnection.">sigc::trackable</a>. </p> <dl class="return"><dt><b>Returns:</b></dt><dd>The reference. </dd></dl> </div> </div> </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>