Minor question about a `MyVal.default`-like syntax

[Dan Smith]

> On Jun 2, 2023, at 2:46 PM, Kevin Bourrillion <kevinb at google.com> wrote:
> 
> This is not too important right now, but I had thoughts, so...
> 
> 
> On Thu, Jun 1, 2023 at 10:59 AM Brian Goetz <brian.goetz at oracle.com> wrote:
> 
> Users should be able to say `new Complex()` and get a default complex value.  (Maybe they can also say `Complex.default`; maybe we won't need that.)  And the same for reflection.
> 
> I think the argument for `MyVal.default` being *unnecessary* might go like this:
> 
> * either there's no implicit constructor and `MyVal.default` won't work
> * or there is, and `MyVal.default` would have to mean the same as `new MyVal()`, so what's the point?
> 
> If that's correct, there might not be a strong argument for keeping it, but I came up with a couple weak ones.
> 
> 1. Arguably, its meaning is more apparent without the reader having to dig into MyVal.java (how much does this matter, in this case?)
> 2. It *feels like* a well-known immutable value that just kind of "exists" and has no need to be constructed. A constant. In fact people might feel tempted to make such constants?

Another weak one:

3. MyVal.default should be a linkage error (or in some worlds, evaluate to 'null') if a B3 class evolves into a B2 class. 'new MyVal()' should be fully compatible—it's the same API point whether the class is B3 or B2, and the caller using this syntax is unlikely to care about its implementation.