I have an abstract class with two concrete subclas...

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[Andrew Ebling]

I have an abstract class with two concrete subclasses containing implementations of fun myFunction() . The body of both implementations is different, but the last line is the same, calling a function in the abstract superclass.

The common last line must be executed last. What is the most appropriate way to use Kotlin language features to refactor out the duplication?

[José González Gómez]

Create an abstract fun in the abstract class which is called by myFunction and override that in the child classes?

[Andrew Ebling]

got it - I see what you mean

[Andrew Ebling]

many thanks!

[Fleshgrinder]

Exactly, same as in Java.

abstract class AC {
    fun myFunction() {
        doMyFunction()
        // post logic
    }

    protected abstract fun doMyFunction()
}

[José González Gómez]

or maybe I didn't understand the question... you have this?

abstract class Parent {
  abstract fun myFunction()
  fun anotherFunction()
}

class FirstChild: Parent {
  fun myFunction() {
    ...
    anotherFunction()
  }
}

class SecondChild: Parent {
  fun myFunction() {
    ...
    anotherFunction()
  }
}

[Andrew Ebling]

@José González Gómez exactly that

[Andrew Ebling]

thanks - although I once did the SCJP certification, I’m coming to Kotlin after a 13 year detour in Objective-C & Swift 😄

[José González Gómez]

ok, then would this work?

abstract class Parent {
  fun myFunction() {
    this.configurableBehavior()
    this.sharedBehavior()
  }
  fun sharedBehavior() {
    ...
  }
  abstract fun configurableBehavior()
}

class FirstChild: Parent {
  fun configurableBehavior() {
    ...
  }
}

class SecondChild: Parent {
  fun configurableBehavior() {
    ...
  }
}

[Andrew Ebling]

@José González Gómez yes - I think this is identical to what @Fleshgrinder suggested above?

[José González Gómez]

yes 🙂

[Andrew Ebling]

great - many thanks to both of you for your help. I see now, I kind of had this inside out. An external reality check is so often super helpful! 👍

[Fleshgrinder]

With Exactly in my comment I meant that @José González Gómez’s comment is exactly correct (I think it was confusing with the sentence that followed 😄 ).