Given a concrete class Animal, how do I define a function that only takes a subclass of Animal?
In typical examples like this Animal is a trait so defining [A <: Animal] implies that you already pass in a subclass of Animal. However, in a scenario like below where Animal is concrete, can I exclude that as being an allowed type?
I'm working with existing generated code, and this is just a generalized example of the problem. Therefore the implication is that I can't make Animal (or the equivalent) into a trait.
See below for an example:
class Animal {
def name: String = "General Animal"
}
class Dog extends Animal {
override def name: String = "Dog"
}
// How do I limit A to be a subtype of Animal (excluding Animal itself)?
class SpecificAnimalContainer[A <: Animal](a: A) {
def specificAnimal: A = a
}
val dogContainer = new SpecificAnimalContainer[Dog](new Dog)
// I do not want this to be able to compile.
val animalContainer = new SpecificAnimalContainer[Animal](new Animal)
Using shapeless you can write:
import shapeless._
class SpecificAnimalContainer[A <: Animal](a: A)(implicit ev: A =:!= Animal) {
def specificAnimal: A = a
}
// val animalContainer = new SpecificAnimalContainer[Animal](new Animal)// doesn't compile
Otherwise you can implement similar type for implicit yourself.