std::swap(std::function)
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std::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)
void swap( std::function <R(Args...)>& lhs, std::function <R(Args...)>& rhs ) noexcept;
Overloads the std::swap algorithm for std::function . Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs).
[edit] Parameters
lhs, rhs
-
polymorphic function wrappers whose states to swap
[edit] Return value
(none)
[edit] 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)[edit] 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 |