std::is_swappable_with, std::is_swappable, std::is_nothrow_swappable_with, std::is_nothrow_swappable

Since C++17

Header: <type_traits>

  1. If the expressions swap(std::declval(), std::declval()) and swap(std::declval(), std::declval()) are both well-formed in unevaluated context after using std::swap; (see Swappable), provides the member constant value equal true. Otherwise, value is false.

# Declarations

template< class T, class U >
struct is_swappable_with;

(since C++17)

template< class T >
struct is_swappable;

(since C++17)

template< class T, class U >
struct is_nothrow_swappable_with;

(since C++17)

template< class T >
struct is_nothrow_swappable;

(since C++17)

# 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 std::is_swappable_with<T, U>::value compiles and evaluates to true.

# Example

This section is incompleteReason: no example

# See also