Draft Spec for Second Preview of String Templates (JEP 459)

[Tagir Valeev]

Looks great, thank you!

Tagir

On Fri, Oct 13, 2023, 11:13 Gavin Bierman <gavin.bierman at oracle.com> wrote:

> Hi Tagir,
>
> Apologies for not replying sooner. Yes, this is an excellent suggestion -
> improving the precision of typing template expressions is a very welcome
> change :-)
>
> I have updated the spec, and the compiler will be updated shortly.
>
> Thanks,
> Gavin
>
> > On 10 Oct 2023, at 06:33, Tagir Valeev <amaembo at gmail.com> wrote:
> >
> > Hello, experts!
> >
> > Probably it's possible to fix the small thing I wrote before? Namely,
> > the type of template expression and its thrown exceptions are
> > determined by the template expression class signature (namely, the
> > instantiation of R and E generic parameters of Processor) and ignoring
> > the actual signature of the process() method, which may have covariant
> > return type and thrown exception type declared. This looks out of sync
> > with the rest of Java. Example:
> >
> > public final class TemplateTest {
> >    interface AnyProcessor extends StringTemplate.Processor<Object,
> > Throwable> {}
> >
> >    static class IntProcessor implements AnyProcessor {
> >       @Override
> >       public Integer process(StringTemplate stringTemplate) {
> >          return 123;
> >       }
> >    }
> >
> >    public static void main(String[] args) {
> >       // error: incompatible types: java.lang.Object cannot be
> > converted to java.lang.Integer
> >       Integer xyz = new IntProcessor()."hello";
> >       // error: unreported exception java.lang.Throwable; must be
> > caught or declared to be thrown
> >       Object xyz2 = new IntProcessor()."hello";
> >    }
> > }
> >
> > I'm not sure whether current behavior is explicitly stated in the spec
> > draft, but the reference implementation behaves this way. I would
> > expect this code to be compilable.
> >
> > Note that we have a similar implicit method invocation construct,
> > try-with-resources, and it respects the actual signature of the
> > close() method (namely, declared exceptions). I think that similarly
> > we should respect the actual method signature here.
> >
> > With best regards,
> > Tagir Valeev.
> >
> > On Mon, Oct 9, 2023 at 4:46 PM Gavin Bierman <gavin.bierman at oracle.com>
> wrote:
> >>
> >> Dear experts:
> >>
> >> The first draft of a spec covering JEP 459 (String Templates (Second
> Preview)) is now available at:
> >>
> >> https://cr.openjdk.java.net/~gbierman/jep459/latest
> >>
> >> Feel free to contact me directly or on this list with any comments.
> >>
> >> Thanks
> >> Gavin
> >>
> >>
> >>> On 5 Oct 2023, at 13:20, Mark Reinhold <mark.reinhold at oracle.com>
> wrote:
> >>>
> >>> https://openjdk.org/jeps/459
> >>>
> >>> Summary: Enhance the Java programming language with string
> >>> templates. String templates complement Java's existing string literals
> >>> and text blocks by coupling literal text with embedded expressions and
> >>> template processors to produce specialized results. This is a preview
> >>> language feature and API.
> >>>
> >>> - Mark
>
>
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