[Kde-pim] [Libical] libical 0.27 is now available

[David Jarvie]

On Mon, March 26, 2007 12:00 pm, Reinhold Kainhofer wrote:
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> Am Montag, 26. März 2007 schrieb David Jarvie:
>> On Sat, March 24, 2007 2:56 pm, Allen Winter wrote:
>> > On Wednesday 21 March 2007 6:06:51 pm Reinhold Kainhofer wrote:
>> >> Am Mittwoch, 28. Februar 2007 schrieb IGnatius T Foobar:
>> >> >  For anyone interested...
>> >> >
>> >> >    http://easyinstall.citadel.org/libical-0.27.tar.gz
>> >> >
>> >> >  tzdata is updated to 2007c (includes the changes for Daylight
>> Savings
>> >> > Time in the US) as well as a couple of minor bugfixes.
>> >>
>> >> I took a look at the files now, and it seems that the DST changes in
>> the
>> >> US
>> >> were implemented wrong. The files contain e.g.
>> >
>> > We need to have a fix right away.
>> > What to do?
>> > http://bugs.kde.org/show_bug.cgi?id=143409
>>
>> This has jogged my memory about a bug I discovered some time ago in the
>> libical time zone definitions. They were updated about a year ago by
>> Tepper Hasso. Many of the definitions are actually completely wrong in
>> the
>> same manner as the new USA definitions. For example, Europe/London also
>> has only a single blanket definition starting in 1970, whereas the
>> previous (correct) version has many different definitions for different
>> years starting in the 19th century. The current version is wrong even
>> for
>> some years post-1970. Tepper's commit needs to be reverted, and then the
>> new USA stuff needs to be added.
>
> Actually, the Olsen database is a comprehensive database of all historical
> DST
> occurrences, too. So basically all that we need is a proper converter from
> the ODB to iCalendar... There are such converters, but I don't know how
> good
> they work.
> See http://www.twinsun.com/tz/tz-link.htm
>
> Only using the system-wide zoneinfo files, it will never be possible to
> properly generate historical times.
>
> I don't have time currently to look into that issue with really broken TZ
> definitions... I suppose unless we find an easy cleaner solution, it is
> best
> now to use the wrong fix and in the future generate proper VTIMEZONE
> snipplets with all historical data directly from the Olsen DB.

But before updating the USA data, Hasso's commit should be reverted. The
current libical definitions in SVN (3.5 and trunk) are completely wrong
for past years.

-- 
David Jarvie.
KAlarm author & maintainer.
http://www.astrojar.org.uk/kalarm

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