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Kotlinx Serialization: How to circumvent reified typeargs for deserialization?

Actually, the main problem is still that there are no reified typeargs for classes in Kotlin (see my other reddit post). But here is why this bothers me in this specific case:

Suppose you have a wrapper class

Wrapper

that takes in a string

content

and a class*

type

and can output an object of class

type

retrieved by parsing

content

as JSON by demand by calling the function

getObj()

:


class Wrapper<T>(private val content: String, /*private val type: KClass<*>*/) { fun getObj(): T { // ? } }

And I want to use kotlinx.serialization. Now, you might have noticed how I put an asterisk after “class” before. Here’s the reason: Yes,

Wrapper

has to take the target class in some way, but how? Should it be just the typearg (won’t work because type erausre) or a

KClass

reference (won’t work because I need a reified typearg)?

The thing is that as far as I know, the only way to decode a generic JSON to a serializable target class is to use

Json.decodeFromString<T>(content)

, where

T

is the target type and

content

is the JSON string. Now,

T

is defined to be reified (so that the type can be processed at runtime) and can only be filled with another reified typearg or an actual class reference. I can’t use another reified typearg because I am in the context of a class and a class cannot have reified typeargs. I can also not use an actual class reference because the user of the class should be able to construct it with different targets, e.g. they decide what the target is, not me.

So, how do I do this with kotlinx.serialization? Is it even possible?

submitted by /u/Raph0007
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