defer (2 of 3 overloads)

Submits a completion token or function object for execution.

template<
    typename Executor,
    typename CompletionToken = DEFAULT>
DEDUCED defer(
    const Executor & ex,
    CompletionToken && token = DEFAULT,
    typename constraint< execution::is_executor< Executor >::value||is_executor< Executor >::value >::type  = 0);

This function submits an object for execution using the specified executor. The function object is queued for execution, and is never called from the current thread prior to returning from defer().

The use of defer(), rather than post , indicates the caller's preference that the executor defer the queueing of the function object. This may allow the executor to optimise queueing for cases when the function object represents a continuation of the current call context.

This function has the following effects:

Constructs a function object handler of type Handler, initialized with handler(forward<CompletionToken>(token)).
Constructs an object result of type async_result<Handler>, initializing the object as result(handler).
Obtains the handler's associated executor object ex1 by performing get_associated_executor(handler).
Creates a work object w by performing make_work(ex1).
Obtains the handler's associated allocator object alloc by performing get_associated_allocator(handler).
Constructs a function object f with a function call operator that performs ex1.dispatch(std::move(handler), alloc) followed by w.reset().
Performs Executor(ex).defer(std::move(f), alloc).
Returns result.get().