Scala case class : copy non equal/ hascode members

Question

I want to use copy on a case classes. But scala insists I specify all the properties that were declared in the second paranthsis.

Example:

package academic.classes.casec.copy

object TstClz {
  val f = DataMe("SD") ( "B")
  val x = f.copy("x 4")()//Error : not enough arguments for method copy: (b: String, c: String)academic.classes.casec.copy.DataMe. Unspecified value parameters b, c.
}

case class DataMe (a : String, a1 : String = "a1")(b:String, c: String = ""){}

Is this a feature or a bug? What can I do to make it work the way I want (get the values of b and c from the instance whose copy is being made?

Answer 1

I don't think that's possible. In this bug report, you can find the following statement:

Martin says: case class ness is only bestowed on the first argument list

the rest should not be copied.

Later, there was a "bug fix" which made copy to return at least a function representing the second parameter list, but that behavior was reverted in this commit.