[/ Boost.Optional Copyright (c) 2015 Andrzej Krzemienski 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:relnotes Release Notes] [heading Boost Release 1.58] * `boost::none_t` is no longer convertible from literal `0`. This avoids a bug where `optional> oi = 0;` would initialize an optional object with no contained value. * Improved the trick that prevents streaming out `optional` without header `optional_io.hpp` by using safe-bool idiom. This addresses [@https://svn.boost.org/trac/boost/ticket/10825 Trac #10825] * IOStream operators are now mentioned in documentation. * Added a way to manually disable move semantics: just define macro `BOOST_OPTIONAL_CONFIG_NO_RVALUE_REFERENCES`. This can be used to work around [@https://svn.boost.org/trac/boost/ticket/10399 Trac #10399] [heading Boost Release 1.57] * [@https://github.com/boostorg/optional/pull/9 Git pull #9]: ['"Supply `` to fix C++03 compile error on `logic_error("...")`"]. [heading Boost Release 1.56] * Added support for rvalue references. Now `optional` works with moveable but non-copyable `T`'s, * Improved `swap` (now uses move operations), * Added function `emplace()`. This is the last of the requests from [@https://svn.boost.org/trac/boost/ticket/1841 Trac #1841], * `optional` is moveable, including conditional `noexcept` specifications, which make it `move_if_noexcept`-friendly, * Using explicit operator bool() on platforms that support it ([@https://svn.boost.org/trac/boost/ticket/4227 Trac #4227]) (breaking change), * Forward declaration of `operator<<(ostream&, optional const&)` to prevent inadvertent incorrect serialization of optional objects, * Removed deprecated function `reset()` from examples ([@https://svn.boost.org/trac/boost/ticket/9005 Trac #9005]), * Equality comparison with `boost::none` does not require that `T` be EqualityComparable, * Optional rvalue references are explicitly disallowed, * Binding temporaries to optional references is explicitly disallowed (breaking change), * More ways to access the contained value, functions `value()`, `value_or()`, `value_or_eval()`, * Updated and reorganized documentation, added tutorial and quick guide sections. [endsect][/ relnotes]