Value classes introduce unwanted public methods

Question

Looking at some scala-docs of my libraries, it appeared to me that there is some unwanted noise from value classes. For example:

implicit class RichInt(val i: In         


        

Answer 1

I'm not sure it's "unwanted noise" as I think you will almost always need to access the underlying values when using your RichInt. Consider this:

// writing ${r} we use a RichInt where an Int is required
scala> def squareMe(r: RichInt) = s"${r} squared is ${r.squared}"
squareMe: (r: RichInt)String

// results are not what we hoped, we wanted "2", not "RichInt@2"
scala> squareMe(2)
res1: String = RichInt@2 squared is 4

// we actually need to access the underlying i
scala> def squareMeRight(r: RichInt) = s"${r.i} squared is ${r.squared}"
squareMe: (r: RichInt)String

Also, if you had a method that adds two RichInt you would need again to access the underlying value:

scala> implicit class ImplRichInt(val i: Int) extends AnyVal {
     |   def Add(that: ImplRichInt) = new ImplRichInt(i + that) // nope...
     | }
:12: error: overloaded method value + with alternatives:
  (x: Int)Int 
  (x: Char)Int 
  (x: Short)Int 
  (x: Byte)Int
 cannot be applied to (ImplRichInt)
         def Add(that: ImplRichInt) = new ImplRichInt(i + that)
                                                        ^

scala> implicit class ImplRichInt(val i: Int) extends AnyVal {
     |   def Add(that: ImplRichInt) = new ImplRichInt(i + that.i)
     | }
defined class ImplRichInt

scala> 2.Add(4)
res7: ImplRichInt = ImplRichInt@6