This is no longer an experimental facility. The names deferred and
deferred_t have been temporarily retained as deprecated entities under
the asio::experimental namespace, for backwards compatibility.
The experimental::deferred completion token takes a call to an
asynchronous operation's initiating function and turns it into a
function object that accepts a completion token. For example:
auto deferred_op =
timer.async_wait(
boost::asio::experimental::deferred);
...
std::move(deferred_op)(
[](std::error_code ec){ ... });
or
auto deferred_op =
timer.async_wait(
boost::asio::experimental::deferred);
...
std::future<void> =
std::move(deferred_op)(
boost::asio::use_future);
The deferred token also supports chaining, to create simple
compositions:
auto deferred_op =
timer.async_wait(
boost::asio::experimental::deferred(
[&](std::error_code ec)
{
timer.expires_after(
std::chrono::seconds(1));
return timer.async_wait(
boost::asio::experimental::deferred);
});
...
std::future<void> = std::move(deferred_op)(boost::asio::use_future);
