Factory method example in spark-shell giving error - scala

Question

I am unable to run below code in spark-shell repl. This is a reproduction from Scala cookbook example provided by Alvin Alexander
I get the error:
<console>:22: error: reference to Animal is ambiguous;
it is imported twice in the same scope by
import $VAL11.Animal
and import INSTANCE.Animal
val test = Animal("dog")
This works fine with Scala repl. Can you please tell me how I can make this example work on spark-shell as well?
Thanks a lot for your help!
trait Animal {
def speak
}
object Animal {
private class Dog extends Animal {
override def speak = {
println("woof")
}
}
private class Cat extends Animal {
override def speak { println("meow") }
}
def apply(s: String):Animal = {
if (s == "dog") return new Dog
else return new Cat
}
}
# repl
Animal("dog")
# compiling
object test {
def main(args: Array[String]){
Animal(args(0)).speak
}
}

Answer 1

As som-snytt pointed out, this is most likely a version of an existing scala bug.
Animal("dog") // show
results in something like this:
import $line15.$read.INSTANCE.$iw.$iw.Animal;
val $line15$read = $line15.$read.INSTANCE;
import $line15$read.$iw.$iw.Animal;
Note that Animal is imported twice. To fix this you can wrap your code in an object:
object test{
trait Animal {
def speak
}
object Animal {
private class Dog extends Animal {
override def speak = {
println("woof")
}
}
private class Cat extends Animal {
override def speak { println("meow") }
}
def apply(s: String):Animal = {
if (s == "dog") return new Dog
else return new Cat
}
}
}
Now, when you call test.Animal("dog") // show you get this instead:
val $line15$read = $line15.$read.INSTANCE;
import $line15$read.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.test;
Note that you get only one, more concise import.
As an interesting side note, if you run your first code and then the second, then test.Animal("dog") results in this:
import $line15.$read.INSTANCE.$iw.$iw.Animal;
val $line16$read = $line16.$read.INSTANCE;
import $line16$read.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.test;
Where the Animal import remains.