<i18n dev> RFR: JDK-8318761: MessageFormat pattern support for CompactNumberFormat, ListFormat, and DateTimeFormatter [v2]

[Naoto Sato]

On Fri, 2 Feb 2024 22:11:17 GMT, Justin Lu <jlu at openjdk.org> wrote:

>> src/java.base/share/classes/java/text/MessageFormat.java line 676:
>> 
>>> 674:      * java.time.format.DateTimeFormatter}. In addition, {@code DateTimeFormatter}
>>> 675:      * does not implement {@code equals()}, and thus cannot be represented as a
>>> 676:      * pattern. Any "default"/"medium" styles are omitted according to the specification.
>> 
>> Since `DateTimeFormatter` eventually are converted to j.t.Format with `toFormat()` method, wouldn't it be possible to implement this method for those dtf(s)?
>
> We discussed this separately, but will go over again here in case others are interested. Since DTF does not implement `equals()`, even if we implement `equals()` for the `ClassicFormat`, we would basically still need to implement our own `equals()` for a DTF to effectively compare the ClassicFormats.
> 
> I had also mentioned that we could reference check the pre-defined DTFs, but this won't work either actually. This is because we cannot reference check the DTFs, but rather the Format adapted DTFs, which mean they are now new ClassicFormats every time since we don't store them.

Thanks. I think it is fine.

>> src/java.base/share/classes/java/text/MessageFormat.java line 1904:
>> 
>>> 1902:             throw new IllegalArgumentException();
>>> 1903:         }
>>> 1904:     }
>> 
>> Same as above.
>
> I would rather use `fromString(String text)` here, as using `Enum.valueOf()` does not work as smoothly as `FormatType`, since the `FormatStyle.text` value does not always match the `FormatStyle` enum name. 
> 
> For example, `FormatStyle.DEFAULT` has a `.text` value of "". So I would have to convert a "" to "default" to check for `FormatStyle.DEFAULT` via `Enum.valueOf()`, but at the same time, this also means that the behavior would now change to accept "default" as `FormatStyle.DEFAULT` (which is not in the spec).
> 
> I could then add extra code to handle the "default" case, but I think at that point it would be much too much complexity compared to this `fromString()` method

Let's keep this static method then.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17663#discussion_r1476805391
PR Review Comment: https://git.openjdk.org/jdk/pull/17663#discussion_r1476805499