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27 lines
888 B
Plaintext
27 lines
888 B
Plaintext
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Boost.Optional
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Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
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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 Implementation Notes]
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`optional<T>` is currently implemented using a custom aligned storage facility
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built from `alignment_of` and `type_with_alignment` (both from Type Traits). It
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uses a separate boolean flag to indicate the initialization state.
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Placement new with `T`'s copy constructor and `T`'s destructor are explicitly used
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to initialize,copy and destroy optional values.
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As a result, `T`'s default constructor is effectively by-passed, but the exception
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guarantees are basic.
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It is planned to replace the current implementation with another with stronger
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exception safety, such as a future `boost::variant`.
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[endsect]
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