from computed constants to stable values

[Maurizio Cimadamore]

Hi Glavo,
I guess we could unpack what we mean a little more. If a jar contains 
several dozens of holder classes, that would affect startup (albeit 
indirectly). You might say "whoa that's a lot of holders" - which would 
be true -- unless you look at code generated by jextract which routinely 
features hundreds (!!) such classes. So in these cases being able _not_ 
to have a class would make a difference.

But, I think your assumption that "one value needs one lambda" is not 
100% correct: you can have a stable list - and use a single lambda to 
initialize an arbitrarily large set of values. This is simply not 
possible with holder classes.

> I've looked at the source code, so I know that StableValue has methods 
> like StableValue::trySet and StableValue::setOrThrow,
> but I haven't seen them in the JEP draft. If they still exist today, 
> can they be included in the description of the JEP?
> For use cases where startup time is critical, they should have lower 
> overhead than StableValue::orElseSet.

Yes, these methods do exist! The JEP focusses on ease of use, so we only 
used the "functional" approach, but I agree that it would be more 
complete to also show what the imperative side of the fence looks like.

Maurizio