This seems like a pretty basic question, but it's ...

# announcements

[Ruckus]

This seems like a pretty basic question, but it's just not clicking for some reason. Say I have

class Ref<T: Ref<T>> { ... }
class RefHolder<T: Ref<T>> { ... }

class Source {
    val refs: MutableList<RefHolder<*>> = ...
    ...
}

fun <T: Ref<T>> serializeRef(ref: RefHolder<T>, ...): ... { ... }

fun serializeSource(source: Source): ... {
  val refs = source.refs.map { serializeRef(it, ...) }  // Cannot resolve type as it: Ref<*>
}

How do I make it so I can call serializeRef?

[Dominaezzz]

You could make serializeRef to be <T : Ref<*>> and ref: T or make Source generic too?

[Ruckus]

Neither of those will work sadly. The source ref list must be able to hold any type of ref, and the serializeRef needs the exact type for further calls.

[Dominaezzz]

Ah, change serializeRef to take ref: T instead ref: Ref<T>. Not sure if it'll fix it but it'll at least shorten your code. 😅

[Dominaezzz]

You probably need covariance or contravariance somewhere in your generics somewhere.

[Ruckus]

Oops, I wrote the code wrong. I've updated it to fix my mistake, so now you can see why ref: T won't work.