On May 7, 2024, at 23:19, Nate Eldredge via Std-Discussion <std-discussion@lists.isocpp.org> wrote:

Along the lines of std::atomic<T>::fetch_add() and friends, I have been wondering about the possibility of an interface that would let you atomically apply an *arbitrary* function to an atomic object.  I'm wondering if such an interface has ever been considered for inclusion in C++.

To explain what I mean, call it fetch_update() by analogy with Java's getAndUpdate().  I'm envisioning that something like

std::atomic<int> x;
int f(int);
x.fetch_update(f);

would atomically perform the equivalent of

x.store(f(x.load());