I failed to find the documentation and AI as well,...

# kotlin-native

[Joel Denke]

I failed to find the documentation and AI as well, asking here. I want to create a class, call it lets say A and I want to be able to use that one as if it was String or Long. And using Kotlin contracts to verify its always like that.
But imagine I am using Map<String, A> instead of using Map<String, Any> where I want to enforce Any to be of type String or Long.
I know I can do this, just not entirely sure how. I think it was combination of value class and kotlin contract somehow?

[Adam S]

are you looking for sealed classes and interfaces? https://kotlinlang.org/docs/sealed-classes.html

[Joel Denke]

No, they cant wrap String, Int, Long etc directly. Or well you can wrap, kind of similar what I have now, but would like to say an variable thats String is actual class A. Send in String but treat it as my own value class or such.

[Joel Denke]

At the moment doing something like:

sealed interface OptionKey
sealed interface OptionValue

@JvmInline
value class StringOption(val value: String): OptionValue

@JvmInline
value class LongOption(val value: Long): OptionValue

@JvmInline
value class ByteArrayOption(val value: ByteArray): OptionValue

@JvmInline
value class BooleanOption(val value: Boolean): OptionValue

fun optionValueOf(value: Any): OptionValue {
    return when(value) {
        is String -> StringOption(value)
        is Long -> LongOption(value)
        is ByteArray -> ByteArrayOption(value)
        is Boolean -> BooleanOption(value)
        else -> error("Unsupported type")
    }
}

But not really what I want 😄

[Joel Denke]

Like typealias OptionValue = String, Long, ByteArray, Boolean 😄

[Big Chungus]

You're looking at union types that are not yet supported in kotlin

[Big Chungus]

https://youtrack.jetbrains.com/issue/KT-13108/Denotable-union-and-intersection-types

[Joel Denke]

@Big Chungus Oh cool wasnt aware of, nice!
I think I was thinking about sealed interface with generic and provide value of type T. And using kotlin contract verifies T is type A, B, C. And create this sealed implementation based on contract fulfilled.

[Joel Denke]

Tested more now, but ended up in nightmare 🤣

[Joel Denke]

Nightmare = unckecked typecast and more classes to get typesafety instead of less