[tz] Java & Rearguard

Clive D.W. Feather clive at davros.org
Thu May 30 19:13:23 UTC 2019

Brandon Smith said:
> The problem as I see it is around the definition of 'what is daylight
> saving time', and the implementation of negative DST offsets changes that
> definition as far as I can tell.  Wikipedia describes it as such
> The commonality there being "advance clocks".
> Perhaps not everyone agrees that those are reliable sources.

What makes you think they are? If I had tried to cite either of those
during my latest degree course, I'd have been penalized significantly.

Both of those have been written by somebody who either isn't aware of all
the subtleties or who doesn't care to explain them all.

> But I think
> the reality is that much if not most of the software industry views them as
> such.

Far too much of the software industry thinks that everyone has a single
forename, a single surname, and a middle initial. What am I supposed to do
when I hit such software? My wife doesn't have a middle initial; I have
two. I know people without a surname and people who have two (I don't mean
double-barrelled; I mean two separate surnames that they chop and change

And don't get me started on software that thinks there are 26 letters in
the alphabet.

> So as others seem to be suggesting to me, libraries and applications
> have forever been written based on the definition and understand that
> clocks move forward with DST transitions.  I know it has been said that
> this is a 'bad assumption',

It is.

> but the reality as I see it is that generally
> speaking all software has been written based upon what developers knew to
> be a 'definition' and not an 'assumption' at all.

You forgot to put quotes round 'knew'. People used to 'know' that the earth
was flat, but that doesn't make it so.

> So not only are we talking about incompatibilities with all the
> software/parsers involved with the libraries themselves (e.g. joda time),
> we are also talking about all software utilizing those libraries who have
> to account for various use cases that rely upon these "definitions".

Yep. Come to the leapseconds list, where we're suffering from exactly the
same mindset from the people who wrote POSIX.

Clive D.W. Feather          | If you lie to the compiler,
Email: clive at davros.org     | it will get its revenge.
Web: http://www.davros.org  |   - Henry Spencer
Mobile: +44 7973 377646

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