Case class copy() method abstraction

Question

I would like to know if it is possible to abstract the copy method of case classes. Basically I have something like sealed trait Op and then something like

Answer 1

Why do you need to create identical copies of your case class instances? Case classes are, by default, immutable so can be safely shared.

In any case, I don't think you can do what you're asking with default parameters:

scala> trait Op { def copy():Op }          
defined trait Op

scala> case class Op1(v:Int) extends Op    
:6: error: class Op1 needs to be abstract, since method copy in trait Op of type ()Op is not defined
       case class Op1(v:Int) extends Op

The compiler doesn't create methods with all combinations of the optional parameters in the defining class. The default values are inserted in the place where the method is called.