std::promise<R>:: promise

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promise ( ) ;
(1) (since C++11)
template < class Alloc >
promise ( std:: allocator_arg_t , const Alloc & alloc ) ;
(2) (since C++11)
promise ( promise && other ) noexcept ;
(3) (since C++11)
promise ( const promise & other ) = delete ;
(4) (since C++11)

Constructs a promise object.

1) Default constructor. Constructs the promise with an empty shared state.
2) Constructs the promise with an empty shared state. The shared state is allocated using alloc . Alloc must meet the requirements of Allocator .
3) Move constructor. Constructs the promise with the shared state of other using move semantics. After construction, other has no shared state.
4) promise is not copyable.

Parameters

alloc - allocator to use to allocate the shared state
other - another promise to acquire the state from

Exceptions

1,2) May throw implementation-defined exceptions.

Example