Reference-default style

Dan Smith daniel.smith at
Mon Feb 10 16:04:42 UTC 2020

> On Feb 9, 2020, at 2:08 PM, John Rose <john.r.rose at> wrote:
> Good point. For our purposes the abstract ctor must always resolve to Object. And it must have the empty signature right?

Right. The abstract constructor is an indication that "instances of this class require no initialization", so there's nothing to be done with parameters. (Equivalently, your search will always end up at Object, so it must match the Object descriptor.)

> A small remaining point: There might be other use cases in the future for other configurations which make logical sense in the same way. If so we can expand the permissions to other constructors besides Object::<init>()V. For now that’s the only one we care about delegating you. 
> Have I got it now?

Yeah, I think so.

What I'm most worried about is *yet another* ad hoc method search being performed by invokespecial. Special-case handling of Object is one thing; a full search mechanism is another.

Something else we might want to do with this feature is a 'new' that executes no code but produces a fully-formed object. It can't be the current 'new' (verifier can't tell if a class requires instance initialization or not), and maybe this is subsumed by a 'new-and-init' instruction, but something to think about...

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