Catalog.kt

import kotlin.reflect.KProperty1
import kotlin.reflect.full.declaredMemberProperties

// A `Catalog` is similar to an `enum class` in the sense that 
//  * every property is available through a static identifier
//  * you can list the `values()`

// A `Catalog` is different from an `enum class` in the sense that
//  * its properties are of a different type
//  * you can distribute properties among several catalog objects

// A catalog is a static enumeration that is non-exhaustive.

// Example usage:

object CatalogA : Catalog<ComplexObject>() {
    val first = ComplexObject(1, "first")
    val second = ComplexObject(2, "second")
    val oops = 42
}

object CatalogB : Catalog<ComplexObject>() {
    val third = ComplexObject(3, "third")
    val fourth = ComplexObject(4, "fourth")
}

// Implementation:

abstract class Catalog<T> {

    @Suppress("UNCHECKED")
    fun values(): Set<T> {
        val catalog = checkNotNull(this::class.objectInstance)
        return this::class.declaredMemberProperties.map {
            val property = it as KProperty1<Any, T>
            property.get(catalog)
        }.toSet()
    }
}

data class ComplexObject(
    val id: Int,
    val name: String,
)

fun caller() {
    val complexObjects = CatalogA.values() + CatalogB.values()
    println(complexObjects.joinToString(separator="\n"))
}

caller()