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documentation update

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[SVN r53239]
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Emil Dotchevski
2009-05-25 06:13:42 +00:00
parent 1229fa445b
commit d990c5a5f9
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doc/frequently_asked_questions.html
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@ -79,6 +79,13 @@ e.add(bar_info(bar));
throw e;</pre>
<p>and looks better than something like:</p>
<pre>throw error().add(foo_info(foo)).add(bar_info(bar));</pre>
<h3>Why is operator&lt;&lt; allowed to throw?</h3>
<p>This question is referring to the following issue. Consider this throw statement example:</p>
<pre>throw file_open_error() <span class="RenoLink"><a href="exception_operator_shl.html">&lt;&lt;</a></span> file_name(fn);</pre>
<p>The intention here is to throw a file_open_error, however if <span class="RenoLink"><a href="exception_operator_shl.html">operator&lt;&lt;</a></span> fails to copy the std::string contained in the file_name <span class="RenoLink"><a href="error_info.html">error_info</a></span> wrapper, a std::bad_alloc could propagate instead. This behavior seems undesirable to some programmers.</p>
<p>Bjarne Stroustrup, The C++ Programming Language, 3rd Edition, page 371:</p>
<blockquote><p><i>"Throwing an exception requires an object to throw. A C++ implementation is required to have enough spare memory to be able to throw bad_alloc in case of memory exhaustion. However, it is possible that throwing some other exception will cause memory exhaustion."</i></p></blockquote>
<p>So, an attempt to throw any exception may already result in propagating std::bad_alloc instead.</p>
</div><div class="RenoAutoDIV"><div class="RenoHR"><hr/></div>
<h3>See Also:</h3>
<div class="RenoPageList"><a href="boost-exception.html">Boost Exception<br/>