Let my code be:
trait Error:
def message: String
sealed trait AssetError extends Error
enum NamespaceError extends AssetError:
case BlankInput
case InvalidCharacter(input: String, char: Char)
extends NamespaceError:
override def message: String = s"...$input ... $char"
case Other(override val message: String)
override def message: String = productPrefix
Doing this, I get the following error:
end of statement expected but ‘:’ found (bloop)
I thought this was the way to implement a body for a enum case but apparently I am doing something wrong.
Am I complete wrong with my assumption or is there just a small error?
Enums don’t let you do that, it’s an intentional restriction:
This is from Programming in Scala 5th Edition.
If you want a subclass body, then you need to fall back to the usual sealed trait pattern explicitly.
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Thank you so much for your help.
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Also note that you can always do the “dynamic dispatch” manually:
trait Error:
def message: String
sealed trait AssetError extends Error
enum NamespaceError extends AssetError:
case BlankInput
case InvalidCharacter(input: String, char: Char)
case Other(override val message: String)
override def message: String = this match
case BlankInput => ""
case InvalidCharacter(input, char) => s"...$input ... $char"
case Other(message) => message
(I wasn’t sure what you wanted to do with productPrefix, so I omited it)
P.S:
It turns out you can override the enum methods with case vals however !
trait Error:
def message: String
sealed trait AssetError extends Error
enum NamespaceError extends AssetError:
case BlankInput
case InvalidCharacter(input: String, char: Char)
case Other(override val message: String)
override def message: String = "hello"
NamespaceError.Other("test").message // "test": String
(NamespaceError.Other("test"): Error).message // "test": String
3 Likes
