Hello everyone While implementing a job scheduler that has to start jobs at specific times (i.e. daily at 08:15) and during specific time ranges (every Monday between 16:20 and 18:00), the need for two new concepts that represents a time (detached from a date) and a time range between two time_of_day came up. While time_duration almost fits these needs, there are some things that we had to take into account: - A time_of_day must be normalized to only allow hours >= 0 && hours < 24 - Only the substract operator makes sense to calculate the duration between to times (15:30 - 12:00 = 3 hours and 30 minutes). 12:20 + 15:32 does not make sense. The implicit conversion to time_duration also allows the usage of time_of_day to create ptime instances (which is IMHO more "understandable" then using time_duration): ptime some_time(date(2008, 4, 1), time_of_day(14, 20, 0)); The implemented classes time_of_day (derived from time_duration) and time_range are very lightweight and allow the user to do things like: BOOST_AUTO_TEST_CASE( time_of_day_test2 ) { time_of_day t1(15,0,0); time_of_day t2(40,0,0); // normalized to 16:00:00 BOOST_MESSAGE("t1 " << t1); // t1 15:00:00 BOOST_MESSAGE("t2 " << t2); // t2 16:00:00 t2 += hours(3) + minutes(30); BOOST_MESSAGE("t1 " << t1); // t1 15:00:00 BOOST_MESSAGE("t2 " << t2); // t2 19:30:00 time_duration d1(t2 - t1); // Duration from 15:00 to 19:30 = 4:30 hour time_duration d2(t1 - t2); // Duration from 19:30 to 15:00 = 19:30 hours BOOST_MESSAGE("d1 " << d1); // d1 04:30:00 BOOST_MESSAGE("d2 " << d2); // d2 19:30:00 time_range afternoon(t1, t2); // From 15:00 to 19:30 time_range over_night(t2, t1); // From 19:30 to 15:00 (over midnight) ptime p1(date(2008, 4, 1), time_of_day(14, 20, 0)); ptime p2(date(2008, 4, 1), time_of_day(16, 40, 0)); BOOST_CHECK(afternoon.contains(p1) == false); BOOST_CHECK(afternoon.contains(p2) == true); BOOST_CHECK(over_night.contains(p1) == true); BOOST_CHECK(over_night.contains(p2) == false); time_range tr1(time_of_day(15, 0, 0), time_of_day(18, 0, 0)); // 15:00 to 18:00 time_range tr2(time_of_day(16, 0, 0), time_of_day(17, 0, 0)); // 16:00 to 17:00 time_range tr3(time_of_day(17, 0, 0), time_of_day(19, 0, 0)); // 17:00 to 19:00 BOOST_CHECK(tr1.contains(tr2) == true); BOOST_CHECK(tr2.contains(tr1) == false); BOOST_CHECK(tr2.contains(tr3) == false); } I think these concepts would fit well into the date time lib. What do you think? Regards James