enable_current_exception.html 4.5 KB

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  17. <h1>Boost Exception</h1>
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  19. <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. -->
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  22. <div class="RenoIncludeDIV"><div class="RenoAutoDIV"><h3>enable_current_exception</h3>
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  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. throw boost::<span class="RenoLink">enable_current_exception</span>(my_exception());</pre>
  46. <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>
  47. <h4>Note:</h4>
  48. <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>
  49. </div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div>
  50. 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>
  51. </div>
  52. <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. -->
  53. <!-- Distributed under the Boost Software License, Version 1.0. (See accompanying -->
  54. <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
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  59. <small>Copyright (c) 2006-2009 by Emil Dotchevski and Reverge Studios, Inc.<br/>
  60. Distributed under the <a href="http://www.boost.org/LICENSE_1_0.txt">Boost Software License, Version 1.0</a>.</small>
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