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

Brian Inglis Brian.Inglis at systematicsw.ab.ca
Sun Nov 2 08:41:43 UTC 2014

On 2014-11-01 16:35, random832 at fastmail.us wrote:
> On Sat, Nov 1, 2014, at 16:24, Paul Eggert wrote:
>> Brian Inglis wrote:
>>> This would require a tradeoff between the compiled sizes of the
>>> decompressors on your platform and the compressed data:
>>>    94K tz.tar.xz
>> We can shrink it even further than that, as follows:
> This requires embedding zic, though. I got the impression his post was
> about compressing the compiled zoneinfo files (which are, after all,
> what is required by the library functions)

He said he was unable to use zic and zoneinfo, so was talking about
simplifying the source data to run against his Python parser, which
could not handle constructs like last weekday of month, or 24.00 time.

If he does that, he is reverting the data to an earlier state that did
not properly reflect the DST rules, loses the benefit of using the
widely distributed and tested code and data, has to maintain his own
patches against the distributed source, and his weak parser, which may
have other bugs in handling the existing source data.

The alternative as others have pointed out is to find some way to use
zic precompiled binary data.

Many other projects have chosen to use compressed binary archive formats:
that approach may meet his unstated needs better, would be generally useful
in the embedded space, and for network updates to similar devices.
That approach could be added to the source code as an alternative to the
standard hosted directory structure, and justify adding another compressed
binary archive to the public distribution.
Take care. Thanks, Brian Inglis

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