Effective Enums in Kotlin with reverse lookup?

Question

I\'m trying to find the best way to do a \'reverse lookup\' on an enum in Kotlin. One of my takeaways from Effective Java was that you introduce a static map inside the enum

Answer 1

True Idiomatic Kotlin Way. Without bloated reflection code:

interface Identifiable {

    val id: T
}

abstract class GettableById(values: Array) where T : Number, R : Enum, R : Identifiable {

    private val idToValue: Map = values.associateBy { it.id }

    operator fun get(id: T): R = getById(id)

    fun getById(id: T): R = idToValue.getValue(id)
}

enum class DataType(override val id: Short): Identifiable {

    INT(1), FLOAT(2), STRING(3);

    companion object: GettableById(values())
}

fun main() {
    println(DataType.getById(1))
    // or
    println(DataType[2])
}