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### 522. Tuple doesn't define swap

Section: 22.4 [tuple], 99 [tr.tuple] Status: CD1 Submitter: Andy Koenig Opened: 2005-07-03 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

Tuple doesn't define swap(). It should.

[ Berlin: Doug to provide wording. ]

[ Batavia: Howard to provide wording. ]

[ Toronto: Howard to provide wording (really this time). ]

[ Bellevue: Alisdair provided wording. ]

Proposed resolution:

Add these signatures to 22.4 [tuple]

>     template <class... Types>
>       void swap(tuple<Types...>& x, tuple<Types...>& y);
>     template <class... Types>
>       void swap(tuple<Types...>&& x, tuple<Types...>& y);
>     template <class... Types>
>       void swap(tuple<Types...>& x, tuple<Types...>&& y);

Add this signature to 22.4.4 [tuple.tuple]

>     void swap(tuple&&);

Add the following two sections to the end of the tuple clauses

> 20.3.1.7 tuple swap [tuple.swap]

>     void swap(tuple&& rhs);

> > Requires: Each type in `Types` shall be `Swappable`.

> > Effects: Calls `swap` for each element in `*this` and its corresponding element in `rhs`.

> > Throws: Nothing, unless one of the element-wise `swap` calls throw an exception.

> 20.3.1.8 tuple specialized algorithms [tuple.special]

>     template <class... Types>
>       void swap(tuple<Types...>& x, tuple<Types...>& y);
>     template <class... Types>
>       void swap(tuple<Types...>&& x, tuple<Types...>& y);
>     template <class... Types>
>       void swap(tuple<Types...>& x, tuple<Types...>&& y);

> > Effects: x.swap(y)