Offset redesign
#11
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lifthrasiir
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Jan 12, 2015
- We have splitted `Offset` into `Offset` and `OffsetState` (name changes in consideration). The former is used to construct and convert local or UTC date, and the latter is used to store the UTC offset inside constructed values. Some offsets are their own states as well. - This uses lots of associated types which implementation is still in flux. Currently it crashes with debuginfo enabled. We've temporarily disabled debuginfo from `Cargo.toml`. - This technically allows a conversion to the local time, but not yet tested.
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lifthrasiir
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Feb 4, 2015
Basically, this should close #11 when officially released. - Formatting syntax is now refactored out of the rendering logic. The main syntax is available in the `format::strftime` module, which also serves as a documentation for the syntax. - A parser (modelled after `strptime(3)`) has been implemented. See the individual commits for the detailed implementation. - There are two ways to get a timezone-aware value from a string: `Offset` or `DateTime<FixedOffset>`. The former should be used when the offset is known in advance (e.g. assume the local date) while the latter should be used when the offset is unknown. Naive types have a simple `from_str` method. - There are some known problems with the parser (even after tons of tests), which will be sorted out in 0.2. Known issues: - This does not exactly handle RFC 2822 and RFC 3339, which subtly differs from the current implementation in case-sensitivity, whitespace handling and legacy syntax. I'd like to integrate #24 for this cause. - Time zone names are not recognized at all. There is even no means to get a name itself, not sure about the resolution. - `Parsed` does *not* constrain `year` to be negative, so manually prepared `Parsed` may give a negative year. But the current verification pass may break such cases. - I absolutely don't know about the parser's performance! - `AUTHORS.txt` has been added, for what it's worth.
lifthrasiir
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Feb 18, 2015
- We have splitted `Offset` into `Offset` and `OffsetState` (name changes in consideration). The former is used to construct and convert local or UTC date, and the latter is used to store the UTC offset inside constructed values. Some offsets are their own states as well. - This uses lots of associated types which implementation is still in flux. Currently it crashes with debuginfo enabled. We've temporarily disabled debuginfo from `Cargo.toml`. - This technically allows a conversion to the local time, but not yet tested.
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The current
Offsetis problematic because we conflate the offset state and offset conversion. Consequently we cannot convert toLocal(!). This is becauseLocalis stored alongside theNaiveDateTimeand should contain a cachedFixedOffset(otherwise every method would slow down).We cannot simply strip the offset state down, or replace it with the mandatory
FixedOffset. Okay, no-overheadDateTime<UTC>might be an illusion, but someOffsetimplementation would want something other thanFixedOffset:Tzfile(#10), for example, would want to store the offset to the most recent transition instead.Associated types do not help either. For example
struct DateTime<Off: Offset> { dt: NaiveDateTime, st: Off::State, off: Off }wouldn't work (duh). It seems that we may have to accept that we should use different types for conversion (.with_offset(...)) and state (DateTime<...>).The text was updated successfully, but these errors were encountered: