Given an enum class, how do I get its entries with...

# getting-started

[Bernhard]

Given an enum class, how do I get its entries without reified types?

enum class Values { TEST }
fun <T: Enum<T>> x(clazz: Class<Enum<T>>) = clazz.entries
x(Values::class)

I'm passing it to a superclass so I can't inline

Edit: My goal is to have an interface or some kind of base class that allows me to serialize/deserialize any enum from/to lowercase strings of its name

[Joffrey]

Not sure I get your goal, do you want to serialize an enum value? Or all enum values of a given enum class?

[Joffrey]

It would be nice to share a bit more of your actual code to see the context and what you're lacking

[Bernhard]

basically I want to pass an enum class to a super class that automatically serializes it from a string

[Bernhard]

I need to interact with JS string enums, so I'm looking at 'test' | 'test2' | 'test3'

[Bernhard]

I want to parse these onto and from kotlin enums

[Bernhard]

I ended up with

inline fun <reified T : Enum<T>> fromCamelCase(value: String): T? =
    enumEntries<T>().find { it.name == value.toEnumConstant() }

fun <T : Enum<T>> Enum<T>.toCamelCase(): String =
    name.split("_").joinToString { it.lowercase() }

[Bernhard]

but obviously you can't make that work in super classes because of the reified type parameter

[Bernhard]

so the idea is to create super methods that parse these onto typesafe values, e.g.

abstract class BaseApp<E: Enum<E>>(
    events: E
) {
    fun onEvent(event: String) {
        onTypedEvent(parseSomehow(event))
    }
    
    fun onTypedEvent(event: E) {} 
}

[Bernhard]

I'm not sure if you can inline super classes and even if you could, it would blow up bundle size

[Joffrey]

Ah so you want to serialize values of the enum, not the enum class as a whole.

I might be stating the obvious, but why not use a serialization library and avoid the trouble?

[Bernhard]

not sure if that is too heavy to just turn a JS string into an enum

[Bernhard]

I've not yet pulled in serialization into my bundle

[Joffrey]

But you're already creating layers of abstraction and passing class objects around. The simplest approach is to just use a simple function with reified type whenever you need it, but you don't seem to be ok with that one.

[Joffrey]

Otherwise, one option is to build what you need at the moment you instantiate your class. Instead of passing the enum class, you could pass entries, or build a simple map to map string values to your enum instances

[Bernhard]

that would be fine, but the reified type parameter sort of limits it's use cases

[Bernhard]

I'll go with that

[Bernhard]

maybe this is a std lib API issue in that case?

[Bernhard]

there seems to be special machinery for enums that works differently

[Bernhard]

anyways, thank you for taking your time

[PHondogo]

You can make global map KClass -> Entries. At the start of app register needed enum classes.