Boost C++ Libraries

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use_future_t

A completion token type that causes an asynchronous operation to return a future.

template<
    typename Allocator = std::allocator<void>>
class use_future_t

Types

Name	Description
allocator_type	The allocator type. The allocator is used when constructing the std::promise object for a given asynchronous operation.

Member Functions

Name	Description
get_allocator	Obtain allocator.
operator()	Wrap a function object in a packaged task.
operator[]	(Deprecated: Use rebind().) Specify an alternate allocator.
rebind	Specify an alternate allocator.
use_future_t [constructor]	Construct using default-constructed allocator. — Construct using specified allocator.

The use_future_t class is a completion token type that is used to indicate that an asynchronous operation should return a std::future object. A use_future_t object may be passed as a completion token to an asynchronous operation, typically using the special value boost::asio::use_future. For example:

std::future<std::size_t> my_future
  = my_socket.async_read_some(my_buffer, boost::asio::use_future);

The initiating function (async_read_some in the above example) returns a future that will receive the result of the operation. If the operation completes with an error_code indicating failure, it is converted into a system_error and passed back to the caller via the future.

Requirements

Header: boost/asio/use_future.hpp

Convenience header: boost/asio.hpp