1[/ 2 Boost.Optional 3 4 Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal 5 Copyright (c) 2015 Andrzej Krzemienski 6 7 Distributed under the Boost Software License, Version 1.0. 8 (See accompanying file LICENSE_1_0.txt or copy at 9 http://www.boost.org/LICENSE_1_0.txt) 10] 11 12[section Header <boost/optional/optional_fwd.hpp>] 13 14[section Synopsis] 15``` 16namespace boost { 17 18template <class T> class optional ; 19 20template <class T> void swap ( optional<T>& , optional<T>& ); 21 22template <class T> struct optional_swap_should_use_default_constructor ; 23 24} // namespace boost 25``` 26 27This header only contains declarations. 28 29[endsect] 30 31 32[endsect] 33