Can I use a type bound on a Scala abstract method and then “tighten up” the definition in a subclass?

How about something like this: class CoordSystem class C3D(val x: Double, y: Double, z: Double) extends CoordSystem class C2D(val x: Double, y: Double) extends CoordSystem trait ShapeLike+C.

Thanks very much Jean-Philippe - this worked like a charm! – Alex Dean Oct 6 at 20:16.

A type parameter is a type parameter, and the super class contract demands that you do not tighten its contract -- making it less strict would not violate the contract, though I don't think it is allowed. You can do something else, however: put the type inside the class. Class Shape class CoordSystem class C3D(val x: Double, y: Double, z: Double) extends CoordSystem class C2D(val x: Double, y: Double) extends CoordSystem abstract class Shape { type C.

Thanks Daniel - I thought about this approach (having seen it in the other post). But I couldn't figure out how to make it play nicely with separate classes using Shape and CoordSystem type parameters. With Jean-Philippe's approach I was able to write e.g. Class BlahC – Alex Dean Oct 6 at 20:24.

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