Functional Kotlin

Abstract classes

So far, so good. Our bakery looks good. However, we have a problem with our current model. Let's look at the following code:

fun main(args: Array<String>) {    val anyGood = BakeryGood("Generic flavour")}

We can instantiate the BakeryGood class directly, which is too generic. To correct this situation, we can mark BakeryGood as abstract:

abstract class BakeryGood(val flavour: String) {   fun eat(): String {     return "nom, nom, nom... delicious $flavour ${name()}"   }   open fun name(): String {     return "bakery good"   } }

An abstract class is a class designed solely to be extended. An abstract class can't be instantiated, which fixes our problem.

What makes abstract different from open?

Both modifiers let us extend a class, but ...