thanks Sean. I am cross posting on dev to see why the code was written that way. Perhaps, this.type doesn’t do what is needed.
Mohit Jaggi Founder, Data Orchard LLC www.dataorchardllc.com On Aug 30, 2016, at 2:08 PM, Sean Owen <so...@cloudera.com> wrote: I think it's imitating, for example, how Enum is delcared in Java: abstract class Enum<E extends Enum<E>> this is done so that Enum can refer to the actual type of the derived enum class when declaring things like public final int compareTo(E o) to implement Comparable<E>. The type is redundant in a sense, because you effectively have MyEnum extending Enum<MyEnum>. Java allows this self-referential definition. However Scala has "this.type" for this purpose and (unless I'm about to learn something deeper about Scala) it would have been the better way to express this so that Model methods can for example state that copy() returns a Model of the same concrete type. I don't know if it can be changed now without breaking compatibility but you're welcome to give it a shot with MiMa to see. It does compile, using this.type. On Tue, Aug 30, 2016 at 9:47 PM, Mohit Jaggi <mohitja...@gmail.com> wrote: Folks, I am having a bit of trouble understanding the following: abstract class Model[M <: Model[M]] Why is M <: Model[M]? Cheers, Mohit.
