I am new to Kotlin, but experienced in other langu...

# serialization

[ewald comhaire]

I am new to Kotlin, but experienced in other languages. For a Kotlin port I tried to replicate a (generic) extension class which is able to persist the members of a data class in a serialized way (local/remote Json files/databases).
Whereas this was straight forward in e.g. C++, Java etc. I have struggled in Kotlin with things like serializing Generic<T> as well as instantiating `T()`but came up with a solution that looks OK (no lint errors) but crashes the Kotlin compiler. Also, I had to take out any reflection based solution as with Kotlin 1.8.20 and 18.21, it is causing stress testing to randomly fail, but I have not managed to create a minimum reproducible example yet...
Conceptually;

@Serializable
data class PersisableSettings @OptIn(ExperimentalSerializationApi::class) constructor(
    // Active Setting
    @EncodeDefault var userName: String = "System",
    @EncodeDefault var vRunName: String = "System Run",
) : Persistable<PersisableSettings>()

@Serializable
abstract class Persistable<T: Any> { //(@Ignore private val initialValues: T, @Ignore val persistableRepository: PersistableRepository<T>) {
    @Ignore private lateinit var persistableRepository: PersistableRepository<T>
    @Ignore private lateinit var settings: T
    operator fun invoke(initialValues: T, persistableRepository: PersistableRepository<T>) : T {
        this.persistableRepository = persistableRepository
        settings = persistableRepository.load() ?: initialValues
        return settings
    }
    fun save(): T = persistableRepository.save(settings)
}

interface PersistableRepository<T> {
    fun save(settings: T): T
    fun load(): T?
}

// Koin instantiation using a local file based storage
single { PersisableSettings()(PersisableSettings(), PersistableFileRepository(androidContext(), "test_settings.json", PersisableSettings.serializer())) }

// Use as
val settings = get<PersisableSettings>()  // Load the settings singleton via Koin
settings.save() // Save the settings

// Example implementation class (a local JSON settings file)
class PersistableFileRepository<T>(private val context: Context, private val name: String,
                                         private val serializer: KSerializer<T>
    //private val dispatcher: CoroutineDispatcher = <http://Dispatchers.IO|Dispatchers.IO>
) : PersistableRepository<T> { ... }

I filed a defect, but more likely I have taken the wrong approach . Sample implementation code that generates the error: github. Any suggestions on how to do this the right way ? Thanks in advance, Ewald

PS. Some progress made: marking the superclass parameters are protected rather than private makes the compiler crash go away, even though IMHO they should be private. Even better, making `Persistable<T> non serializable avoids the compiler crash and seems to be a working solution

[ewald comhaire]

Never mind,, it's was recognized as a defect in the compiler and I ended up coding it differently as it is mandatory for security purposes that that the backend repository field for the data class be private. Managed to work around another defect where the run-time crashed because it claimed to require registered polymorphism whereas all conditions were met for it to be automatic . Need to file another issue for this. The code is working fine now,