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| <a href="http://www.boost.org"><img style="border:0" src="../../../boost.png" alt="Boost" width="277" height="86"/></a> |
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| <h1>Boost Exception</h1> |
| </div> |
| <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> |
| <!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> |
| <!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> |
| <div class="RenoIncludeDIV"><div class="RenoAutoDIV"><h3>error_info</h3> |
| </div> |
| <div class="RenoIncludeDIV"><p><span class="RenoEscape">#<!--<wiki>`#</wiki>--></span>include <<span class="RenoLink"><a href="boost_exception_info_hpp.html">boost/exception/info.hpp</a></span>></p> |
| <pre>namespace |
| boost |
| { |
| <span class="RenoIncludeSPAN"> template <class Tag,class T> |
| class |
| <span class="RenoLink">error_info</span> |
| { |
| public: |
| |
| <span class="RenoIncludeSPAN"> typedef T <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span>;</span> |
| |
| <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 & v );</span> |
| <span class="RenoIncludeSPAN"> <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span> const & <span class="RenoLink"><a href="error_info_value.html">value</a></span>() const; |
| <span class="RenoLink"><a href="error_info_value_type.html">value_type</a></span> & <span class="RenoLink"><a href="error_info_value.html">value</a></span>();</span> |
| };</span> |
| }</pre> |
| </div><h4>Requirements:</h4> |
| <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> |
| <h4>Description:</h4> |
| <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><Tag,T> can be passed to <span class="RenoLink"><a href="exception_operator_shl.html">operator<<</a></span> to be stored in objects of type boost::<span class="RenoLink"><a href="exception.html">exception</a></span>.</p> |
| <h4>Usage:</h4> |
| <p>The header <<span class="RenoLink"><a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a></span>> 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> |
| <pre>#include <<span class="RenoLink"><a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a></span>> |
| |
| struct tag_errno; |
| typedef boost::<span class="RenoLink">error_info</span><tag_errno,int> errno_info;</pre> |
| <p>Or, the shorter equivalent:</p> |
| <pre>#include <<span class="RenoLink"><a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a></span>> |
| |
| typedef boost::<span class="RenoLink">error_info</span><struct tag_errno,int> errno_info;</pre> |
| <p>This errno_info typedef can be passed to <span class="RenoLink"><a href="exception_operator_shl.html">operator<<</a></span> (#include <<span class="RenoLink"><a href="boost_exception_info_hpp.html">boost/exception/info.hpp</a></span>> 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> |
| <pre>throw file_read_error() <span class="RenoLink"><a href="exception_operator_shl.html"><<</a></span> errno_info(errno);</pre> |
| <p>It can also be passed to <span class="RenoLink"><a href="get_error_info.html">get_error_info</a></span> (#include <<span class="RenoLink"><a href="boost_exception_get_error_info_hpp.html">boost/exception/get_error_info.hpp</a></span>> first) to retrieve the tag_errno int from a boost::<span class="RenoLink"><a href="exception.html">exception</a></span>:</p> |
| <pre>catch( boost::<span class="RenoLink"><a href="exception.html">exception</a></span> & x ) |
| { |
| if( int const * e=boost::<span class="RenoLink"><a href="get_error_info.html">get_error_info</a></span><errno_info>(x) ) |
| .... |
| }</pre> |
| <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<<</a></span>:</p> |
| <div class="RenoPageList"><a href="errinfo_api_function.html">errinfo_api_function</a><br/> |
| <a href="errinfo_at_line.html">errinfo_at_line</a><br/> |
| <a href="errinfo_errno.html">errinfo_errno</a><br/> |
| <a href="errinfo_file_handle.html">errinfo_file_handle</a><br/> |
| <a href="errinfo_file_name.html">errinfo_file_name</a><br/> |
| <a href="errinfo_file_open_mode.html">errinfo_file_open_mode</a><br/> |
| <a href="errinfo_nested_exception.html">errinfo_nested_exception</a><br/> |
| <a href="errinfo_type_info_name.html">errinfo_type_info_name</a></div> |
| </div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div> |
| See also: <span class="RenoPageList"><a href="boost-exception.html">Boost Exception</a> | <a href="boost_exception_error_info_hpp.html">boost/exception/error_info.hpp</a> | <a href="boost_exception_exception_hpp.html">boost/exception/exception.hpp</a> | <a href="boost_exception_info_hpp.html">boost/exception/info.hpp</a> | <a href="diagnostic_information.html">diagnostic_information</a> | <a href="diagnostic_information_what.html">diagnostic_information_what</a> | <a href="error_info_error_info.html">error_info::error_info</a> | <a href="error_info_value.html">error_info::value</a> | <a href="error_info_value_type.html">error_info::value_type</a> | <a href="exception.html">exception</a> | <a href="exception_operator_shl.html">exception/operator<<</a> | <a href="exception_ptr.html">exception_ptr</a> | <a href="frequently_asked_questions.html">Frequently Asked Questions</a> | <a href="get_error_info.html">get_error_info</a> | <a href="tutorial_enable_error_info.html">Integrating Boost Exception in Existing Exception Class Hierarchies</a> | <a href="motivation.html">Motivation</a> | <a href="original_exception_type.html">original_exception_type</a> | <a href="tuple_operator_shl.html">tuple/operator<<</a></span> |
| </div> |
| <!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. --> |
| <!-- Distributed under the Boost Software License, Version 1.0. (See accompanying --> |
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