Submits a completion token or function object for execution.
template< typename NullaryToken> DEDUCED defer( NullaryToken && token);
This function submits an object for execution using the object's associated
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.
The completion token that will be used to produce a completion handler. The function signature of the completion handler must be:
void handler();
This function returns async_initiate<NullaryToken, void()>(Init{}, token)
,
where Init
is a function
object type defined as:
class Init { public: template <typename CompletionHandler> void operator()(CompletionHandler&& completion_handler) const; };
The function call operator of Init:
Obtains the handler's associated executor object ex
of type Ex
by performing
auto ex = get_associated_executor(handler);
Obtains the handler's associated allocator object alloc
by performing
auto alloc = get_associated_allocator(handler);
If execution::is_executor<Ex>::value
is true, performs
execution::execute( prefer( require(ex, execution::blocking.never), execution::relationship.continuation, execution::allocator(alloc)), std::forward<CompletionHandler>(completion_handler));
If execution::is_executor<Ex>::value
is false, performs
ex.defer( std::forward<CompletionHandler>(completion_handler), alloc);
void()