<!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.0 Strict//EN' 'http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd'> <html xmlns='http://www.w3.org/1999/xhtml' xml:lang='en' lang='en'> <head> <meta http-equiv='Content-Type' content='text/html; charset=utf-8'/> <title>enable_current_exception</title> <link href='reno.css' type='text/css' rel='stylesheet'/> </head> <body> <div class="body-0"> <div class="body-1"> <div class="body-2"> <div> <div id="boost_logo"> <a href="http://www.boost.org"><img style="border:0" src="../../../boost.png" alt="Boost" width="277" height="86"/></a> </div> <h1>Boost Exception</h1> </div> <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> <!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> <div class="RenoIncludeDIV"><div class="RenoAutoDIV"><h3>enable_current_exception</h3> </div> <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> <pre>namespace boost { <span class="RenoIncludeSPAN"> template <class T> ---unspecified--- <span class="RenoLink">enable_current_exception</span>( T const & e );</span> }</pre> </div><h4>Requirements:</h4> <div><ul><li> T must be a class with an accessible no-throw copy constructor.</li> <li> If T has any virtual base types, those types must have an accessible default constructor.</li> </ul></div> <h4>Returns:</h4> <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> <h4>Description:</h4> <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> <pre>class my_exception: public std::exception { }; .... throw boost::<span class="RenoLink">enable_current_exception</span>(my_exception());</pre> <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> <h4>Note:</h4> <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> </div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div> See 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="frequently_asked_questions.html">Frequently Asked Questions</a> | <a href="tutorial_exception_ptr.html">Transporting of Exceptions Between Threads</a> | <a href="throw_exception.html">throw_exception</a></span> </div> <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> <!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> <div id="footer"> <p> <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> <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> <small>Copyright (c) 2006-2009 by Emil Dotchevski and Reverge Studios, Inc.<br/> Distributed under the <a href="http://www.boost.org/LICENSE_1_0.txt">Boost Software License, Version 1.0</a>.</small> </p> </div> </div> </div> </div> </body> </html>