boost exception

[SVN r43485]

example/error_info_2.cpp

@@ -0,0 +1,49 @@
+//Copyright (c) 2006-2008 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 shows how to add arbitrary data to active exception objects.
+
+#include <boost/exception.hpp>
+#include <boost/shared_ptr.hpp>
+#include <stdio.h>
+#include <errno.h>
+
+//
+
+typedef boost::error_info<struct tag_errno,int> errno_info;
+
+class file_read_error: public boost::exception { };
+
+void
+file_read( FILE * f, void * buffer, size_t size )
+	{
+    if( size!=fread(buffer,1,size,f) )
+        throw file_read_error() << errno_info(errno);
+	}
+
+//
+
+typedef boost::error_info<struct tag_file_name,std::string> file_name_info;
+
+boost::shared_ptr<FILE> file_open( char const * file_name, char const * mode );
+void file_read( FILE * f, void * buffer, size_t size );
+
+void
+parse_file( char const * file_name )
+	{
+    boost::shared_ptr<FILE> f = file_open(file_name,"rb");
+    assert(f);
+    try
+		{
+		char buf[1024];
+        file_read( f.get(), buf, sizeof(buf) );
+		}
+    catch(
+	boost::exception & e )
+		{
+        e << file_name_info(file_name);
+        throw;
+		}
+	}