Scala factory pattern returns unusable abstract type
- by GGGforce
Please let me know how to make the following bit of code work as intended. The problem is that the Scala compiler doesn't understand that my factory is returning a concrete class, so my object can't be used later. Can TypeTags or type parameters help? Or do I need to refactor the code some other way? I'm (obviously) new to Scala.
trait Animal
trait DomesticatedAnimal extends Animal
trait Pet extends DomesticatedAnimal {var name: String = _}
class Wolf extends Animal
class Cow extends DomesticatedAnimal
class Dog extends Pet
object Animal {
def apply(aType: String) = {
aType match {
case "wolf" => new Wolf
case "cow" => new Cow
case "dog" => new Dog
}
}
}
def name(a: Pet, name: String) {
a.name = name
println(a +"'s name is: " + a.name)
}
val d = Animal("dog")
name(d, "fred")
The last line of code fails because the compiler thinks d is an Animal, not a Dog.
