documentation update

[SVN r54906]

example/errinfos.cpp

@@ -0,0 +1,53 @@
+//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)
+
+//This example demonstrates the intended use of various commonly used
+//error_info typedefs provided by Boost Exception.
+
+#include <boost/exception/errinfo_api_function.hpp>
+#include <boost/exception/errinfo_at_line.hpp>
+#include <boost/exception/errinfo_errno.hpp>
+#include <boost/exception/errinfo_file_handle.hpp>
+#include <boost/exception/errinfo_file_name.hpp>
+#include <boost/exception/errinfo_file_open_mode.hpp>
+#include <boost/exception/info.hpp>
+#include <boost/throw_exception.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/weak_ptr.hpp>
+#include <stdio.h>
+#include <errno.h>
+#include <exception>
+
+struct error : virtual std::exception, virtual boost::exception { };
+struct file_error : virtual error { };
+struct file_open_error: virtual file_error { };
+struct file_read_error: virtual file_error { };
+
+boost::shared_ptr<FILE>
+open_file( char const * file, char const * mode )
+	{
+	if( FILE * f=fopen(file,mode) )
+		return boost::shared_ptr<FILE>(f,fclose);
+	else
+		BOOST_THROW_EXCEPTION(
+			file_open_error() <<
+			boost::errinfo_api_function("fopen") <<
+			boost::errinfo_errno(errno) <<
+			boost::errinfo_file_name(file) <<
+			boost::errinfo_file_open_mode(mode) );
+	}
+
+size_t
+read_file( boost::shared_ptr<FILE> const & f, void * buf, size_t size )
+	{
+	size_t nr=fread(buf,1,size,f.get());
+	if( ferror(f.get()) )
+		BOOST_THROW_EXCEPTION(
+			file_read_error() <<
+			boost::errinfo_api_function("fread") <<
+			boost::errinfo_errno(errno) <<
+			boost::errinfo_file_handle(f) );
+	return nr;
+	}