v0.4.0

Original annoucement: https://users.rust-lang.org/t/chrono-0-4-0-is-out/11466.

The new version of Chrono, the date and time library for Rust, has been released.

This version fixes the dependency issues raised in 0.3.1 (in lieu of this release, 0.3.1 is now yanked as well) while moving towards the more idiomatic API convention. This version was developed in relatively heavy time constraints, but I have managed to include several goodies:

• DateTime types can now be serialized to, or deserialized from the integral UNIX timestamp.
• DateTime types and std::time::SystemTime can be freely converted back and forth via From.
• IsoWeek type has been introduced.
• The documentation has been streamlined by removing intermediate implementation modules and accounting for several minor but essential suggestions.

---

This was originally planned as a minor release but was pushed to a major release due to the compatibility concern raised.

Added

• IsoWeek has been added for the ISO week without time zone.

• The += and -= operators against time::Duration are now supported for NaiveDate, NaiveTime and NaiveDateTime. (#99)

  (Note that this does not invalidate the eventual deprecation of time::Duration.)

• SystemTime and DateTime<Tz> types can be now converted to each other via From. Due to the obvious lack of time zone information in SystemTime, the forward direction is limited to DateTime<Utc> and DateTime<Local> only.

Changed

• Intermediate implementation modules have been flattened (#161), and UTC has been renamed to Utc in accordance with the current convention (#148).

  The full list of changes is as follows:

  Before	After
  chrono::date::Date	chrono::Date
  chrono::date::MIN	chrono::MIN_DATE
  chrono::date::MAX	chrono::MAX_DATE
  chrono::datetime::DateTime	chrono::DateTime
  chrono::naive::time::NaiveTime	chrono::naive::NaiveTime
  chrono::naive::date::NaiveDate	chrono::naive::NaiveDate
  chrono::naive::date::MIN	chrono::naive::MIN_DATE
  chrono::naive::date::MAX	chrono::naive::MAX_DATE
  chrono::naive::datetime::NaiveDateTime	chrono::naive::NaiveDateTime
  chrono::offset::utc::UTC	chrono::offset::Utc
  chrono::offset::fixed::FixedOffset	chrono::offset::FixedOffset
  chrono::offset::local::Local	chrono::offset::Local
  chrono::format::parsed::Parsed	chrono::format::Parsed

  With an exception of Utc, this change does not affect any direct usage of chrono::* or chrono::prelude::* types.

• Datelike::isoweekdate is replaced by Datelike::iso_week which only returns the ISO week.

  The original method used to return a tuple of year number, week number and day of the week, but this duplicated the Datelike::weekday method and it had been hard to deal with the raw year and week number for the ISO week date. This change isolates any logic and API for the week date into a separate type.

• NaiveDateTime and DateTime can now be deserialized from an integral UNIX timestamp. (#125)

  This turns out to be very common input for web-related usages. The existing string representation is still supported as well.

• chrono::serde and chrono::naive::serde modules have been added for the serialization utilities. (#125)

  Currently they contain the ts_seconds modules that can be used to serialize NaiveDateTime and DateTime values into an integral UNIX timestamp. This can be combined with Serde's [de]serialize_with attributes to fully support the (de)serialization to/from the timestamp.

  For rustc-serialize, there are separate chrono::TsSeconds and chrono::naive::TsSeconds types that are newtype wrappers implementing different (de)serialization logics. This is a suboptimal API, however, and it is strongly recommended to migrate to Serde.

Fixed

• The major version was made to fix the broken Serde dependency issues. (#146, #156, #158, #159)

  The original intention to technically break the dependency was to facilitate the use of Serde 1.0 at the expense of temporary breakage. Whether this was appropriate or not is quite debatable, but it became clear that there are several high-profile crates requiring Serde 0.9 and it is not feasible to force them to use Serde 1.0 anyway.

  To the end, the new major release was made with some known lower-priority breaking changes. 0.3.1 is now yanked and any remaining 0.3 users can safely roll back to 0.3.0.

• Various documentation fixes and goodies. (#92, #131, #136)