hi there, what is the best way to solve that probl...

# announcements

[Pere Casafont]

hi there, what is the best way to solve that problem?:

open class ParentFoo
class ChildFoo : ParentFoo()

abstract class ParentBar {
	open var foo: ParentFoo? = null
}
class ChildBar : ParentBar() {
	override var foo: ChildFoo?
		get() = super.foo as ChildFoo?
		set(value) {
			super.foo = value
		}
}

right now I'm not allowed to set ChildFoo as the `ChildBar`'s foo property type as it is not exactly the same type as its parent's foo, but as it doesn't have a backing field I think this should be able to compile without any problem. What am I missing there?

[Pere Casafont]

let's better open a thread, the conversation may become long

[Pere Casafont]

@Andreas Sinz @karelpeeters

[Pavlo Liapota]

If it is expected that ChildBar should contain only ChildFoo in foo, then I would have an abstract val foo in `ParentBar`:

open class ParentFoo
class ChildFoo : ParentFoo()

abstract class ParentBar {
    abstract val foo: ParentFoo?
}

class ChildBar : ParentBar() {
    override var foo: ChildFoo? = null
}

That way you will be able to get ParentFoo from ParentBar and get and set ChildFoo from ChildBar.

[Pavlo Liapota]

You can also use generics:

open class ParentFoo
class ChildFoo : ParentFoo()

abstract class ParentBar<TFoo : ParentFoo> {
    var foo: TFoo? = null
}

class ChildBar : ParentBar<ChildFoo>() {
}

[Pere Casafont]

Thank you, sorry for the late response