scala Enumeration retrieving enum by withName when Value has argument

Question

Say i have enum like this:

  object Enm extends Enumeration {
        val ONE, TWO, THREE = Value
  }

and it's possible for me to get disired result by calling with name on it Enm.withName("ONE"), but if i have Value with argument, say:

object Enm extends Enumeration {
     val ONE = Value("1")
     val TWO = Value("2")
     val THREE = Value("3")
}

calling Enm.withName("ONE") i get back noting since it's now "1", "2" and so on. Is it possible somehow to get val names but not the ones i put in Value?

why do you need that? i think perhaps the only way is to pattern match them. — Hongxu Chen, Sep 28 '16 at 13:03
`Enm.values.filter(_.toString.startsWith("1")).max` for now i use this construction but i suspect that there should be more formal approach. — Dmitrii, Sep 28 '16 at 13:09
because of input i've got. So in my case i use Value's argument to print the full name of enum ordinal and i have to find it using input which in my case is the ONE, TWO, THREE — Dmitrii, Sep 28 '16 at 14:47
but in fact you used "startsWith("1")", right? if you need to match "ONE", "TWO", "THREE" literal, perhaps you'd use pattern matching. — Hongxu Chen, Sep 28 '16 at 14:51
i consider it as a temporary solution, if it's not possible i will back to something like `Value("ONE", "1")` and so on with some class that extends Val(string, string). — Dmitrii, Sep 28 '16 at 15:44

Nagarjuna Pamu · Answer 1 · 2016-09-29T10:57:17.610

Hacky solution

Maintain a Map of word string to Number string mapping

object Enm extends Enumeration {
     val ONE = Value("1")
     val TWO = Value("2")
     val THREE = Value("3")
     val map = Map ("ONE" -> "1", "TWO" -> "2", "THREE" -> "3")
}

//Usage
Enm.withName(Enm.map("ONE"))

You cannot override withName method as it is final. So write a custom withName method

 object Enm extends Enumeration {
     val ONE = Value("1")
     val TWO = Value("2")
     val THREE = Value("3")
     private val map = Map ("ONE" -> "1", "TWO" -> "2", "THREE" -> "3")
     def customWithName(str: String) = withName(map(str))
 }

 //Usage
 Enm.customWithName("ONE")

Is there a way to do this without changing the existing enum object? — Jhutan Debnath, Jun 01 '18 at 09:09

scala Enumeration retrieving enum by withName when Value has argument

1 Answers1