[ruby-core:106521] [Ruby master Feature#18033] Time.new to parse a string

Issue #18033 has been updated by Eregon (Benoit Daloze).


nobu (Nobuyoshi Nakada) wrote in #note-22:
> I wrote `Time#inspect`, but the "ISO 8601-like" format is not only used by it, e.g., `--date=iso` of git.

Interesting that `git` has this too:
```
           --date=iso (or --date=iso8601) shows timestamps in a ISO 8601-like format. The differences to the strict ISO 8601 format are:
                        
           窶「   a space instead of the T date/time delimiter
           
           窶「   a space between time and time zone

           窶「   no colon between hours and minutes of the time zone

           --date=iso-strict (or --date=iso8601-strict) shows timestamps in strict ISO 8601 format.
```

Maybe we really need a name for this. Like `Time#iso` and `Time.iso`.

Or it could be a keyword argument: `time.iso8601(format: :git)` and `Time.iso8601(str, format: :git)`.
`:git` is just an example, could be `textual`, `relaxed` or anything.

Another idea would be to actually use the strict variant of iso8601 if that is well defined, like what `git log --date=iso-strict` shows.
Then we'd have `Time#iso8601_strict`/`Time.iso8601_strict`, or `time.iso8601(format: :strict)` and `Time.iso8601(str, format: :strict)`.
That feels proper to me because then we have a clear way to serialize and deserialize times and finding the dumping/parsing method is trivial (they have the same name, no need to guess).
I feel relying on `#inspect` for efficient serializing is in general bad, because that is not the main purpose of `#inspect` (rather it's to show a clear/debug-like representation of an object).

> How about `Time.at`?

To me `Time.at` sounds like "give me a Time at epoch", so I think it's unexpected it does String parsing.

> `Time.try_convert` feels considerable, but passing the timezone option may not fit.

I think an extra optional timezone argument would be fine.



----------------------------------------
Feature #18033: Time.new to parse a string
https://bugs.ruby-lang.org/issues/18033#change-95181

* Author: nobu (Nobuyoshi Nakada)
* Status: Open
* Priority: Normal
----------------------------------------
Make `Time.new` parse `Time#inspect` and ISO-8601 like strings.

* `Time.iso8601` and `Time.parse` need an extension library, `date`.
* `Time.iso8601` can't parse `Time#inspect` string.
* `Time.parse` often results in unintentional/surprising results.
* `Time.new` also about 1.9 times faster than `Time.iso8601`.

    ```
    $ ./ruby -rtime -rbenchmark -e '
    n = 1000
    s = Time.now.iso8601
    Benchmark.bm(12) do |x|
      x.report("Time.iso8601") {n.times{Time.iso8601(s)}}
      x.report("Time.parse") {n.times{Time.parse(s)}}
      x.report("Time.new") {n.times{Time.new(s)}}
    end'
                       user     system      total        real
    Time.iso8601   0.006919   0.000185   0.007104 (  0.007091)
    Time.parse     0.018338   0.000207   0.018545 (  0.018590)
    Time.new       0.003671   0.000069   0.003740 (  0.003741)
    ```

https://github.com/ruby/ruby/pull/4639



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