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 26 boost 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 40 my_exception: 41 public std::exception 42 { 43 }; 44 45 .... 46 throw 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> 51 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="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/> 61 Distributed 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
