swap(std::move_only_function)
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< cpp | utility | functional | move only function
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friend void swap( std::move_only_function & lhs, std::move_only_function & rhs ) noexcept;
(since C++23)
Overloads the std::swap algorithm for std::move_only_function. Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs).
This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::move_only_function<FunctionType> is an associated class of the arguments.
Contents
[edit] Parameters
lhs, rhs
-
std::move_only_function objects whose states to swap
[edit] Return value
(none)
[edit] Example
Run this code
#include <concepts> #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::move_only_function <void(const char*, int) const> f1{foo}; std::move_only_function <void(const char*, int) const> f2{bar}; f1("f1", 1); f2("f2", 2); std::cout << "std::ranges::swap(f1, f2);\n"; std::ranges::swap (f1, f2); // finds the hidden friend f1("f1", 1); f2("f2", 2); }
Output:
foo("f1", 1)
bar("f2", 2)
std::ranges::swap(f1, f2);
bar("f1", 1)
foo("f2", 2)