| Brian Silverman | af2eaa8 | 2018-08-04 17:28:31 -0700 | [diff] [blame^] | 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/none.hpp>] |
| 13 | |
| 14 | [section Synopsis] |
| 15 | ``` |
| 16 | namespace boost { |
| 17 | |
| 18 | class none_t {/* see below */}; |
| 19 | |
| 20 | const none_t none (/* see below */); |
| 21 | |
| 22 | } // namespace boost |
| 23 | ``` |
| 24 | |
| 25 | Class `none_t` is meant to serve as a tag for selecting appropriate overloads of from `optional`'s interface. It is an empty, trivially copyable class with disabled default constructor. |
| 26 | |
| 27 | Constant `none` is used to indicate an optional object that does not contain a value in initialization, assignment and relational operations of `optional`. |
| 28 | |
| 29 | [endsect] |
| 30 | |
| 31 | [endsect] |