std::shared_future::shared_future

From cppreference.com
shared_future();
(1) (since C++11)
shared_future( const shared_future& other );
(2) (since C++11)
shared_future( std::future<T>&& other );
(3) (since C++11)
shared_future( shared_future&& other );
(4) (since C++11)

Constructs a new shared_future.

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, as other, if there's any.
3-4) Transfers the shared state held by other to *this. After the construction, other->valid() == false, also valid() returns the same value as other.valid() would have returned before the construction.

[edit] Parameters

other - another future object to initialize with

[edit] Exceptions

1)
noexcept specification:  
noexcept
  
2) (none)
3-4)
noexcept specification:  
noexcept