How to call super method when overriding a method through a trait

Question

It would appear that it is possible to change the implementation of a method on a class with a trait such as follows:

trait Abstract { self: Result =>
            


        

Answer 1

abstract override is the mechanism, aka stackable traits. It's worth adding that linearization counts, because that's what determines what super means.

This question is a great addendum to the canonical Q&A on self-type vs extension.

Where the inheritance is ambiguous with self-types:

scala> trait Bar { def f: String = "bar" }
defined trait Bar

scala> trait Foo { _: Bar => override def f = "foo" }
defined trait Foo

scala> new Foo with Bar { }
:44: error: <$anon: Foo with Bar> inherits conflicting members:
  method f in trait Foo of type => String  and
  method f in trait Bar of type => String
(Note: this can be resolved by declaring an override in <$anon: Foo with Bar>.)
              new Foo with Bar { }
                  ^

Then obviously, you can choose:

scala> new Foo with Bar { override def f = super.f }
res5: Foo with Bar = $anon$1@57a68215

scala> .f
res6: String = bar

scala> new Foo with Bar { override def f = super[Foo].f }
res7: Foo with Bar = $anon$1@17c40621

scala> .f
res8: String = foo

or

scala> new Bar with Foo {}
res9: Bar with Foo = $anon$1@374d9299

scala> .f
res10: String = foo