ceph/src/boost/libs/exception/doc/enable_current_exception.html

   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">&#35;<!--<wiki>`&#35;</wiki>--></span>include &lt;<span class="RenoLink"><a href="boost_exception_enable_current_exception_hpp.html">boost/exception/enable_current_exception.hpp</a></span>&gt;</p>
  25 <pre>namespace
  26 boost
  27     {
  28 <span class="RenoIncludeSPAN">    template &lt;class T&gt;
  29     ---unspecified--- <span class="RenoLink">enable_current_exception</span>( T const &amp; 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 &amp;).</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>&nbsp;| <a href="boost_exception_enable_current_exception_hpp.html">boost/exception/enable_current_exception.hpp</a>&nbsp;| <a href="configuration_macros.html">Configuration Macros</a>&nbsp;| <a href="copy_exception.html">copy_exception</a>&nbsp;| <a href="current_exception.html">current_exception</a>&nbsp;| <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>