[tz] [Patch] Make it slightly easier to parse tzdata

Lester Caine lester at lsces.co.uk
Mon Nov 3 08:26:20 UTC 2014

On 03/11/14 06:42, Paul Eggert wrote:
> Lester Caine wrote:
>> I have my own
>> reasons for wanting to maintain the existing tz rules after
>> transmission, but is this another one dictating that a proper
>> transparent transmission format is a requirement earlier rather than
>> later?
> It appears to be further support for that sort of thing, yes.  This is
> basically a tzdist issue, not a tz issue, right?  Unless the idea is
> that tz also start distributing binaries?

The basic problem is trying to compartmentalise elements of a system
that needs to work as a whole. tz provides a set of tools and a set of
data that - apart from our different views on historic details - does a
good job at producing a single standard set of material. tzdist fails at
the first hurdle in plugging the very hole it's trying to plug simply
because it is targeting a different end platform. Most operating systems
don't use iCalendar internally?

If tzdist had not started to realise that if it is never going to
provide a single clean source of tz data I think there would be a case
for tz plugging that hole itself. All the tools are in place to simply
provide each update as a diff which to my mind is all that is missing in
allowing a cleaner update mechanism that would eliminate the need for
tzdist? tzdist has to identify properly just what it is providing, and
for the majority of end users it I simply maintaining a clean up to date
copy of tz to use with existing tools? Providing a cut down version of
that as a service for simple devices does not need iCalendar but is now
complicated since one has to know what set of data your 'desktop'
devices are using in order that the simple devices use the same rules?

The original draft proposal for tzdist seemed to be based on the idea
that there WAS a single set of data to work with, and that everybody
would always have the current version. That was only ever going to work
if there WAS only one source of published data, but as a lot of the
traffic here ... like Mikes last night ... users need to know which
version they are using so they know that they may not be seeing the
right results.

And we still need an authoritative pre-1970 source of data. :)

Lester Caine - G8HFL
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