Member fun value() that throws on uninitialized

include/boost/bad_optional_access.hpp

@@ -0,0 +1,28 @@
+// Copyright (C) 2014, Andrzej Krzemienski.
+//
+// Use, modification, and distribution is subject to 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)
+//
+// See http://www.boost.org/libs/optional for documentation.
+//
+// You are welcome to contact the author at:
+//  akrzemi1@gmail.com
+//
+#ifndef BOOST_BAD_OPTIONAL_ACCESS_22MAY2014_HPP
+#define BOOST_BAD_OPTIONAL_ACCESS_22MAY2014_HPP
+
+#include <stdexcept>
+
+namespace boost {
+
+class bad_optional_access : public std::logic_error
+{
+public:
+  explicit bad_optional_access(const std::string& what_arg) : std::logic_error(what_arg) {}
+  explicit bad_optional_access(const char* what_arg) : std::logic_error(what_arg) {}
+};
+
+} // namespace boost
+
+#endif