> Considering time scales, there are three that significantly > interrelate, and no matter what Perl 6 uses internally, it needs to be > able to convert to and from these: > > TAI: continuous count of time using SI seconds as measured by atomic > clocks, 60 seconds in every minute, 60 minutes in every hour, 24 hours > in every day. > > UTC: TAI with an offset, as corrected for the actual revolution of the > Earth: usually 60 seconds in a minute, but occasionally 59 or 61. 60 > minutes in every hour (so 3599, 3600, or 3601 seconds), 24 hours in > every day (86399, 86400, or 86401 seconds). > > time_t: the value you get by taking the UTC time since Jan 1, 1970 at > midnight and converting to a simple count of seconds, pretending there > have been no leap seconds along the way. > > Right now as I type this it is 17:13:38 UTC. That's 17:14:12 in TAI > (which is 34 seconds ahead of UTC until the next leap second). The > corresponding time_t value is 1,235,150,018, but there have actually > been 1,235,150,042 seconds since the UNIX epoch.
Yes, just as I said: a constant offset between each of the proposed epochs. But my point remains: from the user's point of view it doesn't matter which epoch you choose to use behind the scenes, so you might as well pick the one that's easiest on the software (time_t) and leave the transformations to the libraries. Chris
