scala case class equals (==) not working as expected

Question

I must be missing something silly here. I have this:

case class Color(val rgb:Int) {
   private val c = rgb - 0xff000000
   val r = (c & 0xff0000) >> 16
   val g = (c & 0x00ff00) >> 8
   val b = (c & 0x0000ff)
}

case object Red extends Color(0xffff0000)
case object Green extends Color(0xff00ff00)
case object Blue extends Color(0xff0000ff)

Then I expect this to print true:

val c = Color(0xff00ff00)
println(c == Green)

Why doesn't it??

Answer 1

Case classes (or objects) inheriting from case classes is a bad practice, and is illegal as of Scala 2.9.1. Use object instead of case object to define Red, Green and Blue.

Answer 2

Why should that be true? Green is a companion object, c is an instance. They aren't equal.

Answer 3

I think it was a relevant question: "Why case object and case class it extends are not equal".

Using Scala 2.12.2

I added following lines to your example and and now object is equal to the class instance.

object Black extends Color(0x00000000)
val black1 = Color(0x00000000)
black1 == Black

res1: Boolean = true