...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
(Deprecated: Use expiry()
.) Get the timer's expiry time relative
to now.
duration expires_from_now() const;
This function may be used to obtain the timer's current expiry time. Whether the timer has expired or not does not affect this value.