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32 lines
840 B
Plaintext
32 lines
840 B
Plaintext
[/
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Boost.Optional
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Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
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Copyright (c) 2015 Andrzej Krzemienski
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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]
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[section Header <boost/none.hpp>]
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[section Synopsis]
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```
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namespace boost {
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class none_t {/* see below */};
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inline constexpr none_t none (/* see below */);
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} // namespace boost
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```
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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.
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Constant `none` is used to indicate an optional object that does not contain a value in initialization, assignment and relational operations of `optional`.
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[endsect]
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[endsect]
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