Friday 27 June 2014

Noda Time v1.3.0 released

Noda Time 1.3.0 came out today, bringing a healthy mix of new features and bug fixes for all your date and time handling needs. Unlike with previous releases, the improvements in Noda Time 1.3 don’t really have a single theme: they add a handful of features and tidy up some loose ends on the road to 2.0 (on which more below).

So in no particular order…
  • Noda Time 1.3 adds support for the Persian (Solar Hijri) calendar, and experimental support for the Hebrew calender. Support for the latter is “experimental” because we are not entirely convinced that calculations around leap years work as people would expect, and because there is currently no support for parsing and formatting month names. See the calendars page in the user guide for more details.
  • Speaking of parsing and formatting, both should be significantly faster in 1.3.0. Parse failures should also be much easier to diagnose, as errors now indicate which part of the input failed to match the relevant part of the pattern.
  • The desktop build of Noda Time should now be usable from partially-trusted contexts (such as ASP.NET shared hosting), as it is now marked with the AllowPartiallyTrustedCallers attribute.
  • Finally, we also fixed a small number of minor bugs, added annotations for ReSharper users, and added a few more convenience methods — ZonedDateTime.IsDaylightSavingTime() and OffsetDateTime.WithOffset(), for example — in response to user requests. There’s also a new option to make the JSON serializer use a string representation for Interval.
Again, see the User Guide and 1.3.0 release notes for more information about all of the above.

You can get Noda Time 1.3.0 from the NuGet repository as usual (core, testing, JSON support packages), or from the links on the Noda Time home page.

Onward to 2.0

Meanwhile, development has started on Noda Time 2.0. Noda Time 2.0 will not be binary-compatible with Noda Time 1.x, but it will be mostly source-compatible: we don’t plan to make completely gratuitous changes.

Among other things, Noda Time 2.0 is likely to contain:
  • Significant changes to internal representations, with consequences for overall performance (some good, some — hopefully for less-important cases — less good). To take one example: we expect to change the granularity of Instant and Duration from ticks to nanoseconds.
  • A better definition of the range of values that are supported for various types and calendars, and a defined behaviour for when those ranges are exceeded. In a similar vein, we plan to revisit how ordering and equality are implemented (mostly for edge cases).
  • A unified API for changing dates and times similar to the Java 8 “adjuster” concept. (This may replace some methods that are currently on concrete types.)
  • Removal of everything marked as obsolete in 1.x.
We don’t expect to have a release of Noda Time 2.0 until next year, so we may well make some additional releases in the 1.3.x series between now and then, but in general we’ll be focussing on 2.0. If you’re interested in helping out, come and talk to us on the mailing list.

Tuesday 3 June 2014

Hebrew calendar cheat sheet

This post is largely for my own benefit, but I figured it might be interesting to others too, in terms of what you need to think about when coding against the Hebrew calendar. Currently I'm trying to work out what it means to add a year to a date in the Hebrew calendar, at which point it's useful to have some reference tables.

Month names

There are two month numbering systems, which Noda Time calls Civil and Scriptural. In leap years, the number/name mapping in the civil numbering system is offset for the second half of the year, due to Adar being split into Adar I and Adar II.

Number Scriptural Civil (non-leap) Civil (leap)
1 Nisan Tishri Tishri
2 Iyar Heshvan Heshvan
3 Sivan Kislev Kislev
4 Tamuz Tevet Tevet
5 Av Shevat Shevat
6 Elul Adar Adar I
7 Tishri Nisan Adar II
8 Heshvan Iyar Nisan
9 Kislev Sivan Iyar
10 Tevet Tamuz Sivan
11 Shevat Av Tamuz
12 Adar / Adar I Elul Av
13 Adar II   Elul

(Heshvan is sometimes lengthened to Marcheshvan; it's also called Cheshvan. Heshvan is the version in CLDR, which is why I've used it here. Other month names have similar variations, e.g. Tishri vs Tishrei. These are only English versions of Hebrew names, of course.)

Sample years

In unit tests it's useful to have some sample data for specific situations. Here's the data for a complete leap cycle of 19 years. (This period maps to years 1639 to 1659 in the Gregorian calendar.)

Year Leap? Days in Cheshvan Days in Kislev
5400 No 29 30
5401 No 29 29
5402 Yes 30 30
5403 No 29 30
5404 Yes 29 29
5405 No 30 30
5406 No 29 30
5407 Yes 30 30
5408 No 29 29
5409 No 30 30
5410 Yes 29 30
5411 No 30 30
5412 No 29 29
5413 Yes 29 30
5414 No 30 30
5415 Yes 30 30
5416 No 29 29
5417 No 29 30
5418 Yes 30 30
5419 No 30 30