more background to List<int> specializing List<Any>
brian.goetz at oracle.com
Sun Jan 4 18:40:40 UTC 2015
> I know our focus in this current phase is on "Layers", but would like to
> educate myself further about the general background of issues with Any.
Let me correct slightly. We're investigating "layers" or "conditional
methods" not because this is the feature we went looking for, but
because it is a possible and believed-practical answer to the more
general question of "what generic type system can provide us the gradual
migration compatibility we are looking for."
This is not unlike what happened in 8; we didn't do default methods
because we wanted multiple inheritance of behavior; we did it because we
needed *interface evolution*, and of the dozen or so possible ways to
get there that we evaluated, this one had the best combination of
So far we've gotten feedback that people don't like the balance of "user
model weight" and "general utility" for layers (feedback received loud
and clear, no need to reopen this.)
More generally, I think there's a lot of tendency to assume here that
these writeups constitute *decisions*, which they do not. These
writeups are snapshots of where our head is at this week, which we
provide so people can get a peek about what we're thinking about. But
we're a long way from the end of this road.
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