Feature Request: Historical timezone data

[wclr]

So if I see it right this library doesn't use tz database full data that is used by https://momentjs.com/timezone/ and thus can not be used for historical dates, is spacetime intended only for current moment dates conversions?

[spencermountain]

yes, that's correct. I think there are some no-longer-used timezones in our list, but yes, we only record their latest offset+dst change.
I thought i had written that somewhere in the docs, but it appears I haven't. will keep this open until i update it.
cheers

[wclr]

Don't you want to change add this capability (as optional)? This would make spacetime more universal, allowing to use it in projects that work with historical dates.

[spencermountain]

yeah, it gets pretty complex, the further-back you go.
it would also dramatically increase the size of the library

[ryanblock]

To further @spencermountain’s point, the entire reason we created Spacetime at @smallwins was because date/time libraries with full historical databases were too large and slow and clunky. So this suggestion kind of negates the whole point of the thing. Perhaps check out Moment, @whitecolor?

[wclr]

Well, probably there could be created a separate package that would hold the database and use spacetime as a dependency.

@ryanblock I use moment-timezone, it requires moment that I don't use) that is not a huge problem actually, it can be overcome.

I just thought that spacetime as the project could have such a capability.

[spencermountain]

been thinking about this a little, and it'd be fun to implement in a separate package somehow.

if you run this, you'll see most computers (mine, atleast) have dst-change info back as far as 1900:

zdump -v /usr/share/zoneinfo/canada/pacific

it'd be fun to turn this into a cleaner json diff, and see how small we can make it.

I guess the names/ids of tzs change too, so stalingrad time in 1992 would have some weird edges, and things like this.

if anyone wants to work on it with me, holler.

[Fellach]

Hi @spencermountain

What do you mean by no-longer-used timezones? All deprecated on the IANA list?

I've got an error Cannot find timezone named: 'US/Pacific' and not sure is a bug or feature.

Love your work, greetz!

[spencermountain]

@Fellach good question. I think we should include deprecated IANA zones. We have most of them now, i believe. Happy to add 'US/Pacific', and any others from that list.

I'm working on softening things up in a seperate lib for reconciling timezones, like 'India' or 'San Fransisco'. That can be where we put the long-tail, real weird timezones, going forward.
cheers

[johnfumaster]

Yeah, I've also been getting invalid IANA timezone for 'cet'. Strange enough, when I wrote a unit test to cover this, it doesn't complain. I've also tried putting it through informal.find and still I get this error sometimes.

[spencermountain]

agh weird. Yeah, spacetime-informal should be able to convert 'cet' to UTC+3.
I'd really like to know why you're getting such unreliable results!
cheers