Hi Dave, On 2012-12-01, at 22:14, "David T. Lewis" <lewis@mail.msen.com> wrote:
I wanted to see if I can update TimeZoneDatabase (Olson tz data) for Pharo 2.0, but I am encountering a basic time conversion issue. I don't know the background on the Chronology changes in Pharo, so I'll just try to describe the issue as I understand it:
yes we did a big refactoring in 2.0 since the whole time-zone + DateAndTime stuff was severely broken. Moving images from one timezone to another would break all times :P (luckily this happens only twice per year, when moving to daylight saving time)
I am in Michigan, so my time zone offset is 5 hours: DateAndTime now offset ==> -0:05:00:00
Pharo 2.0 does this (wrong): DateAndTime now - (DateAndTime fromSeconds: DateAndTime totalSeconds) ==> 0:05:00:00.334
Previously it did this (right): DateAndTime now - (DateAndTime fromSeconds: DateAndTime totalSeconds) ==> 0:00:00:00.444
Explanation: #totalSeconds reports seconds in local time, but #fromSeconds: in Pharo 2.0 is using UTC. One or the other of these must be wrong.
Possible fix(?): Newer VMs have primitives that report UTC time. Use one of these instead of the local time primitive currently being used.
Yes, so our idea, and I think we are definitely right on that, is that all times use internally UTC. Time-zones are purely for displaying reasons :). => totalSeconds is wrong! (at least at the first glance). could you open a bug report for this?