1<!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.0 Strict//EN' 2'http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd'> 3<html xmlns='http://www.w3.org/1999/xhtml' xml:lang='en' lang='en'> 4<head> 5 <meta http-equiv='Content-Type' content='text/html; charset=utf-8'/> 6 <title>enable_current_exception</title> 7 <link href='reno.css' type='text/css' rel='stylesheet'/> 8</head> 9<body> 10<div class="body-0"> 11<div class="body-1"> 12<div class="body-2"> 13<div> 14<div id="boost_logo"> 15<a href="http://www.boost.org"><img style="border:0" src="../../../boost.png" alt="Boost" width="277" height="86"/></a> 16</div> 17<h1>Boost Exception</h1> 18</div> 19<!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> 20<!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> 21<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 22<div class="RenoIncludeDIV"><div class="RenoAutoDIV"><h3>enable_current_exception</h3> 23</div> 24<div class="RenoIncludeDIV"><p><span class="RenoEscape">#<!--<wiki>`#</wiki>--></span>include <<span class="RenoLink"><a href="boost_exception_enable_current_exception_hpp.html">boost/exception/enable_current_exception.hpp</a></span>></p> 25<pre>namespace 26boost 27 { 28<span class="RenoIncludeSPAN"> template <class T> 29 ---unspecified--- <span class="RenoLink">enable_current_exception</span>( T const & e );</span> 30 }</pre> 31</div><h4>Requirements:</h4> 32<div><ul><li> T must be a class with an accessible no-throw copy constructor.</li> 33<li> If T has any virtual base types, those types must have an accessible default constructor.</li> 34</ul></div> 35<h4>Returns:</h4> 36<p>An object of <i>unspecified</i> type which derives publicly from T. That is, the returned object can be intercepted by a catch(T &).</p> 37<h4>Description:</h4> 38<p>This function is designed to be used directly in a throw-expression to enable the <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> support in Boost Exception. For example:</p> 39<pre>class 40my_exception: 41 public std::exception 42 { 43 }; 44 45.... 46throw boost::<span class="RenoLink">enable_current_exception</span>(my_exception());</pre> 47<p>Unless <span class="RenoLink">enable_current_exception</span> is called at the time an exception object is used in a throw-expression, an attempt to copy it using <span class="RenoLink"><a href="current_exception.html">current_exception</a></span> may return an <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> which refers to an instance of <span class="RenoLink"><a href="unknown_exception.html">unknown_exception</a></span>. See <span class="RenoLink"><a href="current_exception.html">current_exception</a></span> for details.</p> 48<h4>Note:</h4> 49<p>Instead of using the throw keyword directly, it is preferable to call boost::<span class="RenoLink"><a href="throw_exception.html">throw_exception</a></span>. This is guaranteed to throw an exception that derives from boost::<span class="RenoLink"><a href="exception.html">exception</a></span> and supports the <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> functionality.</p> 50</div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div> 51See also: <span class="RenoPageList"><a href="boost-exception.html">Boost Exception</a> | <a href="boost_exception_enable_current_exception_hpp.html">boost/exception/enable_current_exception.hpp</a> | <a href="configuration_macros.html">Configuration Macros</a> | <a href="copy_exception.html">copy_exception</a> | <a href="current_exception.html">current_exception</a> | <a href="tutorial_exception_ptr.html">Transporting of Exceptions Between Threads</a></span> 52</div> 53<!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> 54<!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> 55<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 56<div id="footer"> 57<p> 58<a class="logo" href="http://jigsaw.w3.org/css-validator/check/referer"><img class="logo_pic" src="valid-css.png" alt="Valid CSS" height="31" width="88"/></a> 59<a class="logo" href="http://validator.w3.org/check?uri=referer"><img class="logo_pic" src="valid-xhtml.png" alt="Valid XHTML 1.0" height="31" width="88"/></a> 60<small>Copyright (c) 2006-2009 by Emil Dotchevski and Reverge Studios, Inc.<br/> 61Distributed under the <a href="http://www.boost.org/LICENSE_1_0.txt">Boost Software License, Version 1.0</a>.</small> 62</p> 63</div> 64</div> 65</div> 66</div> 67</body> 68</html> 69
