Hello Does anybody know how can I use inner classes to deleg kotlinlang #getting-started

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Title

Yevhenii Nadtochii

04/30/2020, 2:04 PM

Hello! Does anybody know how can I use inner classes to delegate interface implementation ?

interface Action
class Outer(doer: Doer = this.Doer()) : Action by doer { //'this' is not defined in this context
    inner class Doer : Action
}

interface Action
class Outer : Action by Doer() { //Constructor of inner class Doer can be called only with receiver of containing class
    inner class Doer : Action
}

thanksforallthefish

04/30/2020, 2:32 PM

why does it have to be

inner

inner

classes requires an instance of the outer class to be instantiated. eg

val outer = Outer()
val inner = outer.Inner()

and ofc you don’t yet have an instance of the outer class when you are instatiating the outer class itself

interface Action
class Outer(doer: Doer) : Action by doer {
  inner class Doer : Action
}

is legal, the problem you are having is not delegating, but instantiating

💯 1

Yevhenii Nadtochii

04/30/2020, 2:38 PM

Yes, I understand I can make constructor private and create instances in companion object to resolve instantiating problem. But don't want to. I rather can't get to optimal class structure.

I have Outer class that should implement two interfaces and has some basic PRIVATE functions. I want to delegate each interface to separate classes. But the problem is that they have to use private methods of outer class.

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