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<h1>Boost Exception</h1>
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<!-- 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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<div class="RenoIncludeDIV"><div class="RenoAutoDIV"><h3>diagnostic_information</h3>
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<div class="RenoIncludeDIV"><p><span class="RenoEscape">&#35;<!--<wiki>`&#35;</wiki>--></span>include &lt;<span class="RenoLink"><a href="boost_exception_diagnostic_information_hpp.html">boost/exception/diagnostic_information.hpp</a></span>&gt;<span class="RenoBR">&nbsp;</span><br/><span class="RenoEscape">&#35;<!--<wiki>`&#35;</wiki>--></span>include &lt;<span class="RenoLink"><a href="boost_exception_ptr_hpp.html">boost/exception_ptr.hpp</a></span>&gt;<span class="RenoBR">&nbsp;</span><br/></p>
<pre>namespace
boost
    {
<span class="RenoIncludeSPAN">    template &lt;class E&gt;
    std::string <span class="RenoLink">diagnostic_information</span>( E const &amp; e, bool verbose=true );
    
    std::string <span class="RenoLink">diagnostic_information</span>( <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> const &amp; p, bool verbose=true );</span>
    }</pre>
</div><h4>Returns:</h4>
<p>A string value that contains varying amount of diagnostic information about the passed object:</p>
<div><ul><li> If E can be statically converted to either boost::<span class="RenoLink"><a href="exception.html">exception</a></span> or to std::exception, dynamic_cast is used to access both the boost::<span class="RenoLink"><a href="exception.html">exception</a></span> and std::exception subobjects of e; otherwise, the boost::<span class="RenoLink">diagnostic_information</span> template is not available.</li>
<li> The returned value contains the string representations of all <span class="RenoLink"><a href="error_info.html">error_info</a></span> objects stored in the boost::<span class="RenoLink"><a href="exception.html">exception</a></span> subobject through <span class="RenoLink"><a href="exception_operator_shl.html">operator&lt;&lt;</a></span>.</li>
<li> In addition, if verbose is true, it contains other diagnostic information relevant to the exception, including the string returned by std::exception::what().</li>
</ul></div>
<p>The string representation of each <span class="RenoLink"><a href="error_info.html">error_info</a></span> object is deduced by an unqualified call to to_string(x), where x is of type <span class="RenoLink"><a href="error_info.html">error_info</a></span>&lt;Tag,T&gt;, for which Boost Exception defines a generic overload. It converts x.<span class="RenoLink"><a href="error_info_value.html">value</a></span>() to string, attempting to bind (at the time the <span class="RenoLink"><a href="error_info.html">error_info</a></span>&lt;Tag,T&gt; template is instantiated) the following functions in order:</p>
<div><ol><li>Unqualified call to to_string(x.<span class="RenoLink"><a href="error_info_value.html">value</a></span>()) (the return value is expected to be of type std::string.)</li>
<li>Unqualified call to s &lt;&lt; x.<span class="RenoLink"><a href="error_info_value.html">value</a></span>(), where s is a std::ostringstream.</li>
</ol></div>
<p>The first successfully bound function is used at the time <span class="RenoLink">diagnostic_information</span> is called; if both overload resolutions are unsuccessful, the system is unable to convert the <span class="RenoLink"><a href="error_info.html">error_info</a></span> object to string, and <i>an unspecified stub string value is used without issuing a compile error.</i></p>
<p>The <span class="RenoLink"><a href="exception_ptr.html">exception_ptr</a></span> overload of <span class="RenoLink">diagnostic_information</span> is equivalent to:</p>
<pre>if( p )
    try
        {
        <span class="RenoLink"><a href="rethrow_exception.html">rethrow_exception</a></span>(p);
        }
    catch(...)
        {
        return <span class="RenoLink"><a href="current_exception_diagnostic_information.html">current_exception_diagnostic_information</a></span>(verbose);
        }
else return &lt;unspecified-string-value&gt;;</pre>
<div class="RenoIncludeDIV"><h4>Example:</h4>
<p>this is a possible output from the <span class="RenoLink">diagnostic_information</span> function, as used in <i>libs/exception/example/example_io.cpp:</i></p>
<pre>example_io.cpp(70): Throw in function class boost::shared_ptr&lt;struct _iobuf&gt; __cdecl my_fopen(const char *,const char *)
Dynamic exception type: class boost::exception_detail::clone_impl&lt;struct fopen_error&gt;
std::exception::what: example_io error
[struct boost::<span class="RenoLink"><a href="errinfo_api_function.html">errinfo_api_function</a></span>_ *] = fopen
[struct boost::<span class="RenoLink"><a href="errinfo_errno.html">errinfo_errno</a></span>_ *] = 2, "No such file or directory"
[struct boost::<span class="RenoLink"><a href="errinfo_file_name.html">errinfo_file_name</a></span>_ *] = tmp1.txt
[struct boost::<span class="RenoLink"><a href="errinfo_file_open_mode.html">errinfo_file_open_mode</a></span>_ *] = rb</pre>
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See also: <span class="RenoPageList"><a href="BOOST_THROW_EXCEPTION.html">BOOST_THROW_EXCEPTION</a>&nbsp;| <a href="boost-exception.html">Boost Exception</a>&nbsp;| <a href="boost_exception_diagnostic_information_hpp.html">boost/exception/diagnostic_information.hpp</a>&nbsp;| <a href="configuration_macros.html">Configuration Macros</a>&nbsp;| <a href="current_exception_diagnostic_information.html">current_exception_diagnostic_information</a>&nbsp;| <a href="tutorial_diagnostic_information.html">Diagnostic Information</a>&nbsp;| <a href="diagnostic_information_what.html">diagnostic_information_what</a>&nbsp;| <a href="frequently_asked_questions.html">Frequently Asked Questions</a>&nbsp;| <a href="motivation.html">Motivation</a></span>
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<!-- Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc. -->
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