...one of the most highly
regarded and expertly designed C++ library projects in the
world. — Herb Sutter and Andrei
basic_waitable_timer( const executor_type & ex);
This constructor creates a timer without setting an expiry time. The
expires_after() functions must
be called to set an expiry time before the timer can be waited on.
The I/O executor that the timer will use, by default, to dispatch handlers for any asynchronous operations performed on the timer.