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49 lines
2.2 KiB
Plaintext
49 lines
2.2 KiB
Plaintext
[/
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Boost.Optional
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Copyright (c) 2015 - 2024 Andrzej Krzemieński
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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:std_comp Comparison with `std::optional`]
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[table
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[]
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[ [[*`boost::optional`]] [[*`std::optional`]] [] ]
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[ [`optional<int> o = none;`] [`optional<int> o = nullopt;`] [Different name for no-value tag.] ]
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[ [`optional<X> o {in_place_init, a, b};`] [`optional<int> o {in_place, a, b};`] [Different name for in-place initialization tag.] ]
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[ [] [`optional<vector<int>> o {in_place, {1, 2, 3}};`
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`o.emplace({4, 5, 6});`] [No in-place initialization with initializer-list in `boost`.] ]
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[ [`optional<X> o {in_place_init_if, cond, a, b};`] [] [No syntax for conditional in-place initialization in `std`.] ]
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[ [`optional<X> o {cond, x};`] [] [No syntax for conditional initialization from `T` in `std`.] ]
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[ [`optional<T> o {U{}};`
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`optional<T> o {optional<U>{}};`] [`optional<T> o = U{};`
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`optional<T> o = optional<U>{}`] [Constructors form `U` and `optional<U>` are explicit in `boost` and implicit in `std`.] ]
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[ [] [`optional o = 1;`] [No clever deduction of of `optional`'s template parameters in initialization in `boost`. ]]
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[ [`optional<X const&> o;`] [] [No optional references in `std`.] ]
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[ [] [`constexpr optional<int> o;`] [No `constexpr` interface in `boost`.] ]
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[ [`o.map(&f);`
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`o.flat_map(&of);` ] [`o.transform(&f);`
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`o.and_then(&of);`] [Different names and signatures for monadic interface functions. `boost` takes callbacks by value, `std` by universal reference.] ]
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[ [] [`o.or_else(&of);`] [No `or_else` function in `boost`.] ]
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[ [`o.value_or_eval(&f);`] [] [No `value_or_eval` function in `std`.] ]
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[ [] [`optional<T>{} == U{}`;
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`optional<T>{} == optional<U>{}`] [No comparisons with `U` or `optional<U>` in `boost`.] ]
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[ [`make_optional(cond, v);`] [] [No `make_optional` with condition in `std`.] ]
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[ [] [`make_optional<T>(a, b);`] [No `make_optional` with specified `T` in `boost`.] ]
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[ [`std::cout << optional<int>{};`] [] [No printing to IOStreams in `std`.]]
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]
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[endsect][/ std_comp]
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