Hi guys. How can I override a variable of a derived interface type. I have the interfaces: ```inter...

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[CarlosP]

Hi guys. How can I override a variable of a derived interface type.

I have the interfaces:

interface ExperimentManagerDelegateCore {

interface ExperimentManagerDelegate:ExperimentManagerDelegateCore {

I have the classes:

abstract class ExperimentManagerCore {

    open var delegate: WeakReference<out ExperimentManagerDelegateCore>? = null
}

class ExperimentManager():ExperimentManagerCore() {

    override var delegate: WeakReference<ExperimentManagerDelegate>? = null
}

but in ExperimentManager I got the error:

Type of 'delegate' doesn't match the type of the overridden var-property 'public open var delegate: WeakReference? defined in ExperimentManager.ExperimentManagerCore'

I thought I would fix it with out ExperimentManagerDelegateCore

Any ideas?

[marstran]

I think it's because delegate is a var . The setter causes the out-type to appear in an in-position (the setter's parameter).

[marstran]

At least it compiles if you make it a val

[marstran]

You could actually make it a val in ExperimentManagerCore , and then override it with a var in ExperimentManager 😛

[CarlosP]

I don’t think that would work for me.

But I tried and I don’t make it work with a val.

I get the same error and also I get other errors too because it doesn’t suppose to be a val and I try to change it

[CarlosP]

But thanks for trying 🙂

[marstran]

Actually, another thing you could try is to make ExperimentManagerCore generic. Like this:

abstract class ExperimentManagerCore<T :  ExperimentManagerDelegateCore> {
    open var delegate: WeakReference<T>? = null
}

class ExperimentManager() : ExperimentManagerCore<ExperimentManagerDelegate>() {
    override var delegate: WeakReference<ExperimentManagerDelegate>? = null
}

[CarlosP]

Yes, I think that’s the answer, I was changing everything and it seems to compile.

Thanks.

[CarlosP]

Very clever 🙂