Initialize derived class with base class

Question

Is there a built-in method in Kotlin to do this?

open class Base {
    var data: Int = 0
}

class Derived(arg: Base) : Base() {
    init {
        copyAllProperties(from = arg, to = this)
    }
}

Answer 1

You can write it yourself:

open class Base() {
    var data: Int = 0
}

class Derived(arg: Base) : Base() {
    init {
        super.data = arg.data
    }
}

Or use implementation by delegation[1]:

interface Base {
    var data: Int
}

class BaseImpl : Base {
    override var data: Int = 0
}

class Derived(b: Base) : Base by b