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>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>current_exception</h3> 23</div> 24<div class="RenoIncludeDIV"><p><span class="RenoEscape">#<!--<wiki>`#</wiki>--></span>include <<span class="RenoLink"><a href="boost_exception_ptr_hpp.html">boost/exception_ptr.hpp</a></span>></p> 25<pre>namespace 26boost 27 { 28<span class="RenoIncludeSPAN"> <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> <span class="RenoLink">current_exception</span>();</span> 29 }</pre> 30</div><h4>Requirements:</h4> 31<p>The <span class="RenoLink">current_exception</span> function must not be called outside of a catch block.</p> 32<p>In addition, to safely copy an exception from one thread to another, if the exception object is copied by <span class="RenoLink">current_exception</span> or <span class="RenoLink"><a href="copy_exception.html">copy_exception</a></span>, the two copies must not have shared state. Exceptions that have value-type semantics (as well as the boost::<span class="RenoLink"><a href="exception.html">exception</a></span> type itself) satisfy this requirement.</p> 33<h4>Returns:</h4> 34<div><ul><li> An <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> that refers to the currently handled exception or a copy of the currently handled exception.</li> 35<li> If the function needs to allocate memory and the attempt fails, it returns an <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> that refers to an instance of std::bad_alloc.</li> 36</ul></div> 37<h4>Throws:</h4> 38<p>Nothing.</p> 39<h4>Notes:</h4> 40<div><ul><li> It is unspecified whether the return values of two successive calls to <span class="RenoLink">current_exception</span> refer to the same exception object.</li> 41<li> Correct implementation of <span class="RenoLink">current_exception</span> may require compiler support (e.g. C++11 <a href="https://en.cppreference.com/w/cpp/error/current_exception">std::current_exception()</a> is used when available, as specified by Boost.Config BOOST_NO_CXX11_HDR_EXCEPTION), unless <span class="RenoLink"><a href="enable_current_exception.html">enable_current_exception</a></span> was used at the time the currently handled exception object was passed to throw. Whenever <span class="RenoLink">current_exception</span> fails to properly copy the current exception object, it returns an <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> to an object of type that is as close as possible to the original exception type, using <span class="RenoLink"><a href="unknown_exception.html">unknown_exception</a></span> as a final fallback. All such types derive from boost::<span class="RenoLink"><a href="exception.html">exception</a></span>, and:<div><ul><li> if the original exception object derives from boost::<span class="RenoLink"><a href="exception.html">exception</a></span>, then the boost::<span class="RenoLink"><a href="exception.html">exception</a></span> sub-object of the object referred to by the returned <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> is initialized by the boost::<span class="RenoLink"><a href="exception.html">exception</a></span> copy constructor;</li> 42<li> if available, the exception contains the std::type_info of the original exception object, accessible through <span class="RenoLink"><a href="get_error_info.html">get_error_info</a></span><<span class="RenoLink"><a href="original_exception_type.html">original_exception_type</a></span>>.</li> 43</ul></div> 44</li> 45</ul></div> 46</div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div> 47See also: <span class="RenoPageList"><a href="boost-exception.html">Boost Exception</a> | <a href="boost_exception_ptr_hpp.html">boost/exception_ptr.hpp</a> | <a href="copy_exception.html">copy_exception</a> | <a href="enable_current_exception.html">enable_current_exception</a> | <a href="frequently_asked_questions.html">Frequently Asked Questions</a> | <a href="original_exception_type.html">original_exception_type</a> | <a href="unknown_exception.html">unknown_exception</a></span> 48</div> 49<!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> 50<!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> 51<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> 52<div id="footer"> 53<p> 54<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> 55<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> 56<small>Copyright (c) 2006-2009 by Emil Dotchevski and Reverge Studios, Inc.<br/> 57Distributed under the <a href="http://www.boost.org/LICENSE_1_0.txt">Boost Software License, Version 1.0</a>.</small> 58</p> 59</div> 60</div> 61</div> 62</div> 63</body> 64</html> 65
