27 lines
765 B
Markdown
27 lines
765 B
Markdown
[utility.exchange]
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# 22 General utilities library [[utilities]](./#utilities)
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## 22.2 Utility components [[utility]](utility#exchange)
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### 22.2.3 exchange [utility.exchange]
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[ð](#lib:exchange)
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`template<class T, class U = T>
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constexpr T exchange(T& obj, U&& new_val) noexcept(see below);
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`
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L308)
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*Effects*: Equivalent to:T old_val = std::move(obj);
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obj = std::forward<U>(new_val);return old_val;
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L317)
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*Remarks*: The exception specification is equivalent to:is_nothrow_move_constructible_v<T> && is_nothrow_assignable_v<T&, U>
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