Question

I’ve been reading the C++11 spec, and I’m having trouble understanding the result of one of the std::promise object operators (std::promise& operator=(std::promise&& rhs) noexcept).

The spec says the effect is “Abandons any shared state and then as if promise(std::move(rhs)).swap(*this).”

I get that *this will equal the previous value of rhs, but what is the effect on rhs?

Answer 1

promise& operator=(promise&& rhs) tranfers the ownership of the std::promise from one object to another. After the assigment rhshas no associated async result, and *this has the one rhs had before (if any).