Given a class hierarchy where the base class defines a recursive self-type: abstract class A<T extends A<T>> { } How can I declare another class (which should not be generic in T, because such a T could vary over the lifetime of the object) with a field that can hold any subclass of A? The following does not work: public class B { ...
Self-types seem to be important so I want to know why they are useful. From what I can gather, a self-type for a trait A: trait B trait A { this: B => } says that "A cannot be mixed into a concrete class that does not also extend B". (sidenote: I'm also seeing this fail in the REPL when mixed into an abstract class that does not e...
In Scala, I've seen the constructs trait T extends S and trait T { this: S => used to achieve similar things (namely that the abstract methods in S must be defined before an instance may be created). What's the difference between them? Why would you use one over the other? ...
Say I have the following traits: trait A trait B { this: A => } trait C extends B // { this: A => } Compiler error: illegal inheritance; self-type C does not conform to B's selftype B with A As expected if I uncomment the self type annotation, the compiler is happy. I think it's quite obvious why C also needs this self type. What ...