[tz] Vanguard vs. "main" vs. rearguard

[Brandon Smith]

> By the way, is anybody still using rearguard format? If not, perhaps
> it's time to retire this stuff now. (That would save us all the hassle
> of conversations like this one. :-)

Yes.  We are unfortunately still dependent on the rearguard format.
We are actively working to get away from that need and have been for
some time now, but the size and complexity of the amount of code
required to be updated here makes this a difficult and time consuming
task.  Unfortunately, we are dealing with years of legacy code that
make a lot of bad assumptions about how DST works and the introduction
of negative values greatly exposed this resulting in a substantial
number of required changes on our part.  So in the interim, we are
still reliant upon rearguard until we can work through all the
necessary changes to be fully compatible with vanguard formats.
Making the switch to vanguard today absent of those changes would
introduce a number of defects for us.

I know this is not something this community wishes to support forever
and I certainly understand that.  But for the immediate time we are
still dependent upon rearguard and would respectively ask for your
support and patience while we continue to work through our necessary
updates.

Thanks,
-Brandon


On Thu, May 20, 2021 at 1:17 PM Paul Eggert via tz <tz at iana.org> wrote:
>
> On 5/20/21 10:50 AM, Kerry Shetline wrote:
> > Is there a particular reason that the following situation is handled with bespoke awk processing:
>
> The goal was to keep the data source simple, and put hacks into
> ziguard.awk when that's easy. I would rather not have these hacks bleed
> into the data source.
>
> > It would be great if the special comments would be all one needed to parse the data for rearguard, main, or vanguard.
>
> I see where you're coming from, but that's not the goal here. I didn't
> want to invent a preprocessor for zic, creating technology that would
> have to be documented and supported and have backwards-compatibility
> problems of its own. The vanguard/main/rearguard stuff is just a
> hopefully-temporary hack that, once it evaporates, will require zero
> maintenance.
>
> By the way, is anybody still using rearguard format? If not, perhaps
> it's time to retire this stuff now. (That would save us all the hassle
> of conversations like this one. :-)