Can I have a case class with default/hardcoded values

Question

For example say I have a sealed trait AnimalSoundsand I have case class "Dog" and a case class "Cat" I want the two case classes value to default to "Woof" and "Cat"

sealed trait AnimalSounds extends Product with Serializable
final case class Dog(sound: String = "woof") extends AnimalSounds
final case class Cat(sound: String = "meow") extends AnimalSounds

println(Dog.sound)

I get the error "sound is not a member of object"

I would suggest that you read the basis first of how to access members of a case class! — joesan, Aug 20 '19 at 10:34
If you want that sound to behave like a constant that nobody could change and that is available without creating an instance, create it on the **Companion object** instead. — Luis Miguel Mejía Suárez, Aug 20 '19 at 10:40

score 7 · Accepted Answer · answered Aug 20 '19 at 11:01

If by "hardcoded" it is meant constants consider case objects like so

sealed trait AnimalSounds { val sound: String }
case object Dog extends AnimalSounds { val sound = "woof" }
case object Cat extends AnimalSounds { val sound = "meow" }

Dog.sound

which outputs

res0: String = woof

score 2 · Answer 2 · answered Aug 20 '19 at 10:35

2

In order to work with a case class instance, you first need to create one:

val d: Dog = Dog()
println(d.sound)

answered Aug 20 '19 at 10:35

Yuval Itzchakov

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score 0 · Answer 3 · answered Aug 20 '19 at 10:36

0

Since you have provided the defaults in your case class, you can also so

Dog().sound

answered Aug 20 '19 at 10:36

joesan

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Can I have a case class with default/hardcoded values

3 Answers3