6. Default access modes in records. (See above. ) I specifically want to make sure we are doing the best thing on access defaults (what happens when you don’t mention *any* access mode). I suppose that’s a separate item, related to this one. Even though we have a decision of record on this, I’m calling it out here and now because we are stuck with the final decision we make this time around. (Maybe like a mandatory appeal for a capital case.)
Choices: A. Package scope like classes, B. public like interfaces, C,D,… something new for records. A. Records are concise classes which represent a state vector of components, plus optional additional behavior. If a record member is declared with no access mode, it is given the package access mode. Just like classes. The word “public” must be reaffirmed for every API in the record; just like classes, the presumption is that API points should be private by default, and only made public via explicit mark-up. B. Records are state vectors of components, plus optional additional behavior. They are not general classes, but rather constrained types, much like interfaces are behavior vectors of abstract API points, plus optional behavior. If a record member is declared with no access mode, it is given the public access mode. Just like an interface, a record is a restricted type, whose contracts with the outside world are mainly public, and which has a limited capacity for non-public contracts. C. Records are state vectors of components, plus optional additional behavior. The parts of their API which are intended to be mostly public are public by default, at least if the record type as a whole is public. The precedent for this variability is the implicit empty nullary constructor supplied to every class, whose access mode is copied from the class itself. The parts of a record API that are expected to be public are the factory (canonical constructor) and the accessors (component projection methods). So those guys are public by default (if the record is public). (If the record isn’t public those other guys are the same.) At present I prefer “B”, because I now think that, regarding the access expectiations of API points, records are *far more similar to interfaces* than they are to random run of the mill classes. We started with random classes, but after applying enough constraints we now have API elements which are closely analogous to interfaces: Bundles of state, bundles of operations. And, for wide use; i.e. few or no secrets. In both cases, “public” is the sane default. An advantage of “B” is there’s nothing new to teach. “You know how interfaces have their own default access? Well, records use the same rules.” — John
