Yes, this would work as a hack — implicitly declare a private ctor that initializes the fields only, and let users write factories that do validation / normalization. The hacky part is that there has to be an order of the fields, and we’d probably take the order in which the fields are declared in the source file, which is kind of brittle. So I’d say that this definitely goes in the “expedient MLW tricks” category, rather than a viable user model for LW10.
> On May 19, 2018, at 9:31 AM, Dan Smith <daniel.sm...@oracle.com> wrote: > >> On May 18, 2018, at 2:05 PM, Brian Goetz <brian.go...@oracle.com> wrote: >> >> >>> Thesis: Value constructors are the same notation as VBC constructors. >> >> +1. I don't think its a good use of our "user model complexity budget" to >> have a different way to write these guys. It also facilitates migration. >> And "Codes like a class" has a pretty sensible answer for "how do I write a >> constructor." > > A simpler approach, in the spirit of "let's not waste effort on problems we > don't know how we're going to solve": you get one implicit constructor, and > it's private. You can't declare custom constructors. Write factory methods > for your clients.
