# std::experimental::ranges::is_swappable_with, std::experimental::ranges::is_swappable, std::experimental::ranges::is_nothrow_swappable_with, std::experimental::ranges::is_nothrow_swappable

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< cpp‎ | experimental‎ | ranges

Defined in header `<experimental/ranges/type_traits>` |  |
template <class T, class U> struct is_swappable_with; | (1) | (ranges TS)
template <class T> struct is_swappable; | (2) | (ranges TS)
template <class T, class U> struct is_nothrow_swappable_with; | (3) | (ranges TS)
template <class T> struct is_nothrow_swappable; | (4) | (ranges TS)

1) If the expressions ranges::swap(std::declval<T>(), std::declval<U>()) and ranges::swap(std::declval<U>(), std::declval<T>()) are both well-formed when treated as an unevaluated operand, provides the member constant `value` equal true. Otherwise, `value` is false. Access checks are performed as if from a context unrelated to either type.
2) If `T` is not a referenceable type (i.e., possibly cv-qualified void or a function type with a cv-qualifier-seq or a ref-qualifier), provides a member constant `value` equal to false. Otherwise, provides a member constant `value` equal to ranges::is_swappable_with<T&, T&>::value.
3) Same as (1), but evaluations of both expressions from (1) are known not to throw exceptions.
4) Same as (2), but uses is_nothrow_swappable_with.

`T` and `U` shall each be a complete type, (possibly cv-qualified) void, or an array of unknown bound. Otherwise, the behavior is undefined.

### Helper variable templates

template <class T, class U> constexpr bool is_swappable_with_v = is_swappable_with<T, U>::value; | (1) | (ranges TS)
template <class T> constexpr bool is_swappable_v = is_swappable<T>::value; | (2) | (ranges TS)
template <class T, class U> constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<T, U>::value; | (3) | (ranges TS)
template <class T> constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<T>::value; | (4) | (ranges TS)

## Inherited from std::integral_constant

### Member constants

value [static] | true if `T` is swappable with `U` , false otherwise (public static member constant)

### Member functions

operator bool | converts the object to bool, returns `value` (public member function)
operator() (C++14) | returns `value` (public member function)

### Member types

Type | Definition
`value_type` | `bool`
`type` | std::integral_constant<bool, value>

### Notes

This trait does not check anything outside the immediate context of the swap expressions: if the use of `T` or `U` would trigger template specializations, generation of implicitly-defined special member functions etc, and those have errors, the actual swap may not compile even if `ranges::is_swappable_with<T,U>::value` compiles and evaluates to `true`.

### Examples

| This section is incomplete Reason: no example

### See also

Swappable SwappableWith | specifies that a type can be swapped or that two types can be swapped with each other (concept)
is_swappable_with is_swappable is_nothrow_swappable_with is_nothrow_swappable (C++17)(C++17)(C++17)(C++17) | checks if objects of a type can be swapped with objects of same or different type (class template)

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