std::experimental::future<T>::operator=

std::experimental::future<T>& operator=( std::experimental::future<T>&& other ) noexcept;	(1)
std::experimental::future<T>& operator=( const std::experimental::future<T>& other ) = delete;	(2)

赋值另一个 future 对象的内容。

1) 释放任何共享状态，并将 other 的内容移动赋值给 *this。赋值后，other.valid() == false 并且 this->valid() 将产生与赋值前 other.valid() 相同的值。

2) std::experimental::future 不是 CopyAssignable。

other - 一个 std::experimental::future，它将状态转移到 *this

*this

std::future 扩展
experimental::future
experimental::shared_future
experimental::when_all
experimental::when_any
experimental::make_ready_future
experimental::make_exceptional_future
闩锁和栅栏
experimental::latch
experimental::barrier
experimental::flex_barrier
原子智能指针
experimental::atomic_shared_ptr
experimental::atomic_weak_ptr