SourceVersion::feature

[Joseph D. Darcy]

On 10/14/2021 10:23 AM, Michael Bien wrote:
> is this the right mailing list for javax.lang.model.* discussions?


The compiler-dev list would be appropriate as well, but core-libs will work.

First, I understand the desire for a method like this. One of the 
potential issues is SourceVersion models language versions and while, to 
date, there has been a simple linear progression, that is not guaranteed 
to be case arbitrarily far into the future, even though it is the most 
likely outcome.

Since java.lang.Runtime.Version is in the platform now, I think this 
request would be better satisfied via a

     public static SourceVersion valueOf(Runtime.Version version)

method on SourceVersion. That way the modeling of SourceVersion can 
absorb any non-linearity in versioning and presumably provide sufficient 
information for a  Runtime.Version -> SourceVersion mapping to query.

I've filed the RFE

     JDK-8275308: Add valueOf(Runtime.Version) factory to SourceVersion

Cheers,

-Joe


>
> if yes:
>
> instead of adding
>     /**
>      * Returns the version as int representing the feature release.
>      * @see Runtime.Version#feature()
>      */
>     public int feature() {
>         return this.ordinal();
>     }
> to SourceVersion.
>
> a note could be added to the doc that the ordinal can be used as 
> feature version. Since this statement would apply to the past too, the 
> note could be backported to all maintained JDKs. This comes with the 
> usual downside of not being able to add enums for in-between versions 
> in future.
>
> (doing both would be an option too of course)
>
>
> To not use the ordinal, client code has to go through some enum init 
> rituals to be able to do version comparisons:
>
>    final static SOURCE_VERSION_RELEASE_18;
>    static {
> SourceVersion tmp18;
>         try {
>             tmp18 = SourceVersion.valueOf("RELEASE_18");
>         } catch (IllegalArgumentException ex) {
> tmp18 = null;
>         }
>         SOURCE_VERSION_RELEASE_18 = tmp18;
>         //... more versions
>    }
> just to be able to
>
>     if (SOURCE_VERSION_RELEASE_18 != null && 
> version.compareTo(SOURCE_VERSION_RELEASE_18) >= 0) {}
>
> or
>
>     if 
> (Integer.parseInt(version.name().substring(version.name().indexOf('_')+1)) 
> >= 18) {}
>
> which is shorter but not a good solution either.
>
> what the client code actually wants is:
>
>     if (SourceVersion.latest().feature() >= 18) {}
>
>
> it was a wise decision for java.lang.Runtime.Version to not use enums :)
>
> best regards,
> michael
>
>
>
> On 09.10.21 20:58, Michael Bien wrote:
>> Hello,
>>
>> could javax.lang.model.SourceVersion receive a feature() method 
>> returning the version as an int, analog to java.lang.Runtime.Version?
>>
>> if (SourceVersion.latest().feature() >= 18) {}
>>
>> is simpler than comparing enums which may or may not exist dependent 
>> on the deployed java version and cleaner than ordinal() tricks.
>>
>> best regards,
>>
>> michael
>>