```expect interface A { fun doSomething() }``` ...

# multiplatform

[Andreas Jost]

expect interface A {
   fun doSomething()
}

actual interface A {
   actual fun doSomething() { /*do sth. */ }
}

This code causes an error, because the expected function is abstract by default and the actual function has an implementation, which means that modality is different. Can I somehow define the expect function as non-abstract? Usually you would give a function of an interface a body to make it non-abstract. If you do that, the error at the actual declaration is gone, but expected declarations must not have bodies, so that's another error.

[Kris Wong]

interfaces can't have implementations

[Kris Wong]

is there a reason you want to use expect/actual on an interface?

[Andreas Jost]

@Kris Wong "Interfaces in Kotlin can contain declarations of abstract methods, _as well as method implementations._" from https://kotlinlang.org/docs/reference/interfaces.html#interfaces
This feature is quite handy in my opinion.
In the expect/actual context I just found a kinda hacky solution using an extension function:

interface A
expect A.doSomething()

actual A.doSomething() { ... }

[Kris Wong]

huh... how did I not know that

[Kris Wong]

too much Java on the brain i suppose

[Arkadii Ivanov]

Java has 'default' interface methods