shared_future( const shared_future& other );
shared_future( std::future<T>&& other );
shared_future( shared_future&& other );
Constructs a new
1) Default constructor. Constructs an empty shared future, that doesn't refer to a shared state, that is valid() == false.
2) Constructs a shared future that refers to the same shared state, if any, as
3-4) Transfers the shared state held by
otherto *this. After the construction, other.valid() == false, and this->valid() returns the same value as other.valid() would have returned before the construction.
|other||-||another future object to initialize with|