Wrap class hierarchies using opaque types

package thirdpartylibrary
abstract class BaseClass
final class SubClass1
  extends BaseClass
final class SubClass2(val param: String)
  extends BaseClass

package opaquetypehierarchy
import thirdpartylibrary.{BaseClass, SubClass1, SubClass2}
opaque type WrappedBaseClass = BaseClass
opaque type WrappedSubClass1 

Have you checked if it works if you put them in the same file? If not, then I do not think you can make this work easily, and, TBH, I would just use normal wrapper classes, it is likely the overhead of the boxing is not that bad.

Thanks, @Yuriy!

I deliberately excluded constructors, etc. to keep this an MVE. I didn't realize the definitions had to go in the same file, and that fixed my issue.

Thanks @Luis! Doh! I wasn't aware that they needed to be in the same file! It looks like that's all I'm going to need...