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

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  15 <a href="http://www.boost.org"><img style="border:0" src="../../../boost.png" alt="Boost" width="277" height="86"/></a>
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  17 <h1>Boost Exception</h1>
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  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>error_info</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_info_hpp.html">boost/exception/info.hpp</a></span>&gt;</p>
  25 <pre>namespace
  26 boost
  27     {
  28 <span class="RenoIncludeSPAN">    template &lt;class Tag,class T&gt;
  29     class
  30     <span class="RenoLink">error_info</span>
  31         {
  32         public:
  33
  34     <span class="RenoIncludeSPAN">    typedef T <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span>;</span>
  35
  36     <span class="RenoIncludeSPAN">    <span class="RenoLink"><a href="error_info_error_info.html">error_info</a></span>( <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span> const &amp; v );</span>
  37     <span class="RenoIncludeSPAN">    <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span> const &amp; <span class="RenoLink"><a href="error_info_value.html">value</a></span>() const;
  38         <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span> &amp; <span class="RenoLink"><a href="error_info_value.html">value</a></span>();</span>
  39         };</span>
  40     }</pre>
  41 </div><h4>Requirements:</h4>
  42 <p>T must have accessible copy constructor and must not be a reference (there is no requirement that T's copy constructor does not throw.)</p>
  43 <h4>Description:</h4>
  44 <p>This class template is used to associate a Tag type with a value type T. Objects of type <span class="RenoLink">error_info</span>&lt;Tag,T&gt; can be passed to <span class="RenoLink"><a href="exception_operator_shl.html">operator&lt;&lt;</a></span> to be stored in objects of type boost::<span class="RenoLink"><a href="exception.html">exception</a></span>.</p>
  45 <h4>Usage:</h4>
  46 <p>The header &lt;<span class="RenoLink"><a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a></span>&gt; provides a declaration of the <span class="RenoLink">error_info</span> template, which is sufficient for the purpose of typedefing an instance for specific Tag and T, for example:</p>
  47 <pre>#include &lt;<span class="RenoLink"><a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a></span>&gt;
  48
  49 struct tag_errno;
  50 typedef boost::<span class="RenoLink">error_info</span>&lt;tag_errno,int&gt; errno_info;</pre>
  51 <p>Or, the shorter equivalent:</p>
  52 <pre>#include &lt;<span class="RenoLink"><a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a></span>&gt;
  53
  54 typedef boost::<span class="RenoLink">error_info</span>&lt;struct tag_errno,int&gt; errno_info;</pre>
  55 <p>This errno_info typedef can be passed to <span class="RenoLink"><a href="exception_operator_shl.html">operator&lt;&lt;</a></span> (#include &lt;<span class="RenoLink"><a href="boost_exception_info_hpp.html">boost/exception/info.hpp</a></span>&gt; first) to store an int named tag_errno in exceptions of types that derive from boost::<span class="RenoLink"><a href="exception.html">exception</a></span>:</p>
  56 <pre>throw file_read_error() <span class="RenoLink"><a href="exception_operator_shl.html">&lt;&lt;</a></span> errno_info(errno);</pre>
  57 <p>It can also be passed to <span class="RenoLink"><a href="get_error_info.html">get_error_info</a></span> (#include &lt;<span class="RenoLink"><a href="boost_exception_get_error_info_hpp.html">boost/exception/get_error_info.hpp</a></span>&gt; first) to retrieve the tag_errno int from a boost::<span class="RenoLink"><a href="exception.html">exception</a></span>:</p>
  58 <pre>catch( boost::<span class="RenoLink"><a href="exception.html">exception</a></span> &amp; x )
  59     {
  60     if( int const * e=boost::<span class="RenoLink"><a href="get_error_info.html">get_error_info</a></span>&lt;errno_info&gt;(x) )
  61         ....
  62     }</pre>
  63 <p>For convenience and uniformity, Boost Exception defines the following commonly used <span class="RenoLink">error_info</span> typedefs, ready for use with <span class="RenoLink"><a href="exception_operator_shl.html">operator&lt;&lt;</a></span>:</p>
  64 <div class="RenoPageList"><a href="errinfo_api_function.html">errinfo_api_function</a><br/>
  65 <a href="errinfo_at_line.html">errinfo_at_line</a><br/>
  66 <a href="errinfo_errno.html">errinfo_errno</a><br/>
  67 <a href="errinfo_file_handle.html">errinfo_file_handle</a><br/>
  68 <a href="errinfo_file_name.html">errinfo_file_name</a><br/>
  69 <a href="errinfo_file_open_mode.html">errinfo_file_open_mode</a><br/>
  70 <a href="errinfo_nested_exception.html">errinfo_nested_exception</a><br/>
  71 <a href="errinfo_type_info_name.html">errinfo_type_info_name</a></div>
  72 </div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div>
  73 See also: <span class="RenoPageList"><a href="boost-exception.html">Boost Exception</a>&nbsp;| <a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a>&nbsp;| <a href="boost_exception_exception_hpp.html">boost/exception/exception.hpp</a>&nbsp;| <a href="boost_exception_info_hpp.html">boost/exception/info.hpp</a>&nbsp;| <a href="diagnostic_information.html">diagnostic_information</a>&nbsp;| <a href="diagnostic_information_what.html">diagnostic_information_what</a>&nbsp;| <a href="error_info_error_info.html">error_info::error_info</a>&nbsp;| <a href="error_info_value.html">error_info::value</a>&nbsp;| <a href="error_info_value_type.html">error_info::value_type</a>&nbsp;| <a href="exception.html">exception</a>&nbsp;| <a href="exception_operator_shl.html">exception/operator&lt;&lt;</a>&nbsp;| <a href="exception_ptr.html">exception_ptr</a>&nbsp;| <a href="frequently_asked_questions.html">Frequently Asked Questions</a>&nbsp;| <a href="get_error_info.html">get_error_info</a>&nbsp;| <a href="tutorial_enable_error_info.html">Integrating Boost Exception in Existing Exception Class Hierarchies</a>&nbsp;| <a href="motivation.html">Motivation</a>&nbsp;| <a href="original_exception_type.html">original_exception_type</a>&nbsp;| <a href="tuple_operator_shl.html">tuple/operator&lt;&lt;</a></span>
  74 </div>
  75 <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. -->
  76 <!-- Distributed under the Boost Software License, Version 1.0. (See accompanying -->
  77 <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
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