std::swap(std::function)
From cppreference.com
< cpp | utility | functional | function
| Defined in header <functional>
|
||
| template< class R, class... Args > void swap( std::function<R(Args...)>& lhs, std::function<R(Args...)>& rhs ) noexcept; |
(since C++11) | |
Overloads the std::swap algorithm for std::function. Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs).
Parameters
| lhs, rhs | - | polymorphic function wrappers whose states to swap |
Return value
(none)
Example
Run this code
#include <functional> #include <iostream> void foo(const char* str, int x) { std::cout << "foo(\"" << str << "\", " << x << ")\n"; } void bar(const char* str, int x) { std::cout << "bar(\"" << str << "\", " << x << ")\n"; } int main() { std::function<void(const char*, int)> f1{foo}; std::function<void(const char*, int)> f2{bar}; f1("f1", 1); f2("f2", 2); std::cout << "std::swap(f1, f2);\n"; std::swap(f1, f2); f1("f1", 1); f2("f2", 2); }
Output:
foo("f1", 1)
bar("f2", 2)
std::swap(f1, f2);
bar("f1", 1)
foo("f2", 2)Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2062 | C++11 | overload of swap for function was not required to be noexcept
|
required |
See also
| swaps the contents (public member function) | |
| specializes the std::swap algorithm (function) |