it’s pronounced: “jiff”
I really likes this package. And I may use it immediately. Very complete and detailed documentation. It lacks in some conveniences like iso8601, rfc3339 or other presets for formatting. But those can be handled manually. Thanks for this!
You should absolutely not need to handle ISO 8601 and RFC 3339 manually. They are supported via the Display and FromStr trait implementations on every main type in Jiff (Span, Zoned, Timestamp, civil::DateTime, civil::Date and civil::Time). It’s technically an implementation of a mixture of ISO 8601, RFC 3339 and RFC 9557, but the grammar is specified precisely by Temporal. See: https://docs.rs/jiff/latest/jiff/fmt/temporal/index.html
Speaking of convenient things best not handled manually, do you have any plans to get support for it into crates like sqlx-postgresql, diesel or humantime where conversions need to happen but pretty much the same way for every user of the library?
Yeah this is a tough one. I’m not sure the right thing to do is for me to go around blasting PRs at those projects. They’re probably already carrying support for both chrono and time, and asking them to support a third that is brand new is a bit of a stretch I think. Especially since I’ve promised breaking changes in the not-too-distant future. (Although I would like to do a Jiff 1.0 release about 1 year from now and commit to stability.) At least, I know I’d be hesitant if I were on the other side of it. But maybe folks are more flexible than me, I’m not sure.
I’ve been noodling on just adding these integrations to jiff itself. I do worry that if I do that, then the integrations will always stay with Jiff, even at 1.0. But maybe there just isn’t another feasible choice.
But, why do you mention humantime? humantime doesn’t have any integrations with time or chrono. humantime is more like a thin wrapper on top of std::time::Duration and std::time::SystemTime to make parsing and printing a bit nicer.
@burntsushi is it pronounced yiff?
From COMPARE.md:
Conversely, in Jiff, all time zone lookups by name are cached.
Is the cache invalidated if system tzdata is updated?
And what effect does the answer have on the example from “Jiff supports detecting time zone offset conflicts” if both zoned datetimes used the system timezone which got updated between 1. opening 2. parsing the two zoned datetimes.
Jiff losslessly roundtrips time zone aware datetimes
In this section, wouldn’t be more realistic for chrono users to use timezone info around the wire instead of on the wire, rather than using Local+FixedOffset?
Is the cache invalidated if system tzdata is updated?
Yes, although at present, there is a TTL. So an update may take “time” to propagate. jiff::tz::db().reset() will force the cache to be invalidated. I expect the cache invalidation logic to get tweaked as we get real experience with it.
And what effect does the answer have on the example from “Jiff supports detecting time zone offset conflicts” if both zoned datetimes used the system timezone which got updated between 1. opening 2. parsing the two zoned datetimes.
It’s hard to know precisely what you mean. But once you get a jiff::tz::TimeZone, that value is immutable: https://docs.rs/jiff/latest/jiff/tz/struct.TimeZone.html#a-timezone-is-immutable
New updates to tzdb are only observed when you do a tzdb lookup.
In this section, wouldn’t be more realistic for chrono users to use timezone info around the wire instead of on the wire, rather than using Local+FixedOffset?
That’s kinda my point. How do they do that? And does it work with chrono-tz and tzfile? And what happens if tzdb updates lead to a serialized datetime with an incorrect offset in a future update of tzdb? There are all sorts of points of failure here that Jiff will handle for you by virtue of tighter integration with tzdb as a first class concept.
In this section, wouldn’t be more realistic for
chronousers to use timezone info around the wire instead of on the wire, rather than usingLocal+FixedOffset?
They do say that the difference is that chrono users would need to keep out-of-band timezone information in addition to the datetime, whereas Jiff does it in-band.
That’s fine. I didn’t look at the code, but from what I gather, Jiff serializes the timezone name (not detailed tz info). chrono users would communicate the same thing, but it’s not built-in functionality in the dt type itself.
The example I referred to however may imply that chrono users would be inclined do the wrong thing, and get the wrong result as a sequence.
(humble personal opinion bit) It feels like it’s a case where the example was pushed a bit extra to fit into the “jump into the pit of success/despair” reference. A reference many, young and old, wouldn’t recognize, or otherwise wouldn’t care for anyway.
You should look at it, they say the implement RFC 9556 timestamps, which include tz info. In my experience it IS useful in real use, because a fixed offset timestamp can lose a bit of information.
For example, if you have a timestamp and want to add a few months to it, for example for a reminder, you will get a timestamp at the same time in the same offset. In many cases that will be wrong, because of things like daylight savings time, which change the offset of the timezone. You will get a timestamp an hour before or after the moment you intended, and it will be in the “wrong” offset in that timezone in that time of year. With timezone aware timestamps, they are aware that the offset will change, and will be able to give a timestamp in the future at the correct time and offset.
