JEP 430 String Templates, some weird scenarios feedback

[Stephen Colebourne]

On Thu, 15 Jun 2023 at 23:49, Brian Goetz <brian.goetz at oracle.com> wrote:
> On 6/15/2023 6:01 PM, Anatoly Kupriyanov wrote:
>
> I understand why it works like that but it still causes some confusion to me, at least it should be somehow documented:
>
> var val = 1; var template = RAW."val = \{val}"; assert template.interpolate().equals("val = 1");
> val = 2; assert template.interpolate().equals("val = 1");//weird
>
>
> Yes, a template closes over values, not variables.  We could adopt the same constraint as we do with lambdas / inner classes -- require that any referenced variables be effectively final -- but this would likely be quite restrictive given the typical use cases for string templates.

FWIW, the example here pushes me to encourage you to adopt effectively
final - and the parallel with lambdas means that no one will be
surprised by choosing effectively final for templates.

I am surprised by the claim that "typical use cases" make this
restrictive. Can you expand? Given that the value is captured not the
variable, it is hard to imagine use cases where effectively final
would be problematic. If there are problematic use cases, perhaps it
would be better to add a language change that gives the developer more
control over effectively final (various options available),

Stephen