Proposed new KDateTime class

Tobias Koenig tokoe at
Thu Dec 8 08:24:48 GMT 2005

On Thu, Dec 08, 2005 at 12:10:30AM +0000, David Jarvie wrote:
> On Wednesday 07 Dec 2005 22:01, Tobias Koenig wrote:
Hi David,

> The problem is that the data held for different time zone classes (because of 
> the different types of data in the source databases) varies. For example, for 
> KSystemTimezone, the class doesn't actually hold data on daylight savings 
> time changes. It gets information as and when required about UTC offsets, 
> etc., from library calls.
Well, so the external helper class would just pass in the data without
daylight saving time changes and when this information is not available,
KTimezone will automatically use the UTC offsets for calculating... or
do I miss something here?

Maybe you could summarize shortly which data (timezones, daylight saving
changes, additional data) may vary in the subclassed KTimezone classes.

> It would require a lot of processing for it to call
> library functions to get a complete list of time changes.
Yes, so the KSystemTimezone would do... so where is the difference?

> If, of course, the system library gets its information from the zonetab database, it could read 
> the relevant tzfile using the KTzfileTimezone class, and compile a complete 
> list of time changes from it. But if the system time zone database comes from 
> some other source, there is no obvious solution.
What do you mean with other source?

> To sum up, there is no fixed set of data belonging to a time zone class. So 
> it's difficult to see how to proceed.
Not a fixed set, but maybe a greatest common factor which can be used in

I know this workaround breaks the nice OO way of doing software
development, however a class which can't be used in most cases (and
serialization will be an important action in KDEPIM 4.0) is quite

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