Is there a quick and easy way to solve "This type parameter violates the Finite Bound Restriction" I...

# random

[enighma]

Is there a quick and easy way to solve "This type parameter violates the Finite Bound Restriction"
I have the following use-case (converting some code from Java to Kotlin):

MyClass<T : MyClass<*>>(
    listener: MyListener<T>
)

Essentially my class has a listener which has a callback with the class. It's not beautiful, but it's what I have to work with atm.

[Youssef Shoaib [MOD]]

I've never seen that error before! Does writing it as MyClass<T : MyClass<T>> solve the issue? It should because that encoding of self types is very common

[enighma]

That does not work. That is what gives me the error

I was able to solve it this way:

interface Base

MyClass<T: Base>:Base (
  listener: MyListener<T>
)

[Youssef Shoaib [MOD]]

I'm not seeing any errors with:

interface MyListener<T: MyClass<T>>
abstract class MyClass<T : MyClass<T>>(
    val listener: MyListener<T>
)

but glad you found a solution regardless!

[Youssef Shoaib [MOD]]

I think your issue is using a star-projected type there. When mentioning the bound itself, I get no error. I.e T: MyClass<T> works, but T: MyClass<*> doesn't

[enighma]

You might be right. Let me double check. Maybe I converted it wrong when I anonymized it

[enighma]

@Youssef Shoaib [MOD] I think it was the * that broke things. I'm building now, but it looks correct 🙂 Thanks for calling that out!