1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
|
[/
Boost.Optional
Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
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)
]
[section Implementation Notes]
`optional<T>` is currently implemented using a custom aligned storage facility
built from `alignment_of` and `type_with_alignment` (both from Type Traits). It
uses a separate boolean flag to indicate the initialization state.
Placement new with `T`'s copy constructor and `T`'s destructor are explicitly used
to initialize,copy and destroy optional values.
As a result, `T`'s default constructor is effectively by-passed, but the exception
guarantees are basic.
It is planned to replace the current implementation with another with stronger
exception safety, such as a future `boost::variant`.
[endsect]
|
