Under ‘Runtime hierarchy checks’
The example given states that if we have a reference to a supertype and then change it to a subtype, we are unable to call methods or use properties that are specific to the subtype, which makes a lot of sense. However, in practice, that does not seem to necessarily be the case:
The example below compiles (and runs) just fine on my computer
fun main() {
open class SuperType(open val name: String) {
fun someMethodAllSuperTypesHave() {}
}
class SubType(override val name: String) : SuperType(name) {
val subtypeField = 10
fun someMethodOnlySubtypesHave() {
println(subtypeField)
}
}
var generalType: SuperType = SuperType("George")
generalType.someMethodAllSuperTypesHave()
generalType = SubType("James")
generalType.someMethodOnlySubtypesHave()
}
