Dynamic Constants adoption IRL

[Remi Forax]

----- Mail original -----
> De: "Maxim Degtyarev" <mdegtyarev at gmail.com>
> À: "amber-dev" <amber-dev at openjdk.java.net>
> Envoyé: Jeudi 15 Avril 2021 17:04:15
> Objet: Dynamic Constants adoption IRL

> Hello,
> 
> Is there currently real-life examples of dynamic constants adoption in
> programming languages targeting JVM or either libraries and
> frameworks?
> Or are there currently no projects using dynamic constants? Maybe any
> planned in the future?
> Quick googling was unsuccessful.

It depends what you mean by dynamic constant.
For the VM, a simple static final field that is not a primitive types or String is a dynamic constant.

A lambda that doesn't capture any variable value is a dynamic constant.

A VarHandle, used for concurrency or by the Foreign Memory API is a dynamic constant, the same goes for the MethodHandles.

The Vector API relies on the VectorSpecies being a dynamic constant.

System.out and System.err, the ClassValue for a particular class, or Thread.currentThread() can all be seen as dynamic constants (but they are not constant for the JIT).

The classData of an hidden class is also a dynamic constant [1].

regards,
Rémi

[1] https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/invoke/MethodHandles.html#classData(java.lang.invoke.MethodHandles.Lookup,java.lang.String,java.lang.Class)