CODEWITHSUNDEEP
scalaconstantstraits
Freewind
Freewind

Reputation: 198228

How to get the constant value from a trait?

I defined a trait RequireLogin with a constant:

trait RequireLogin {
    val message = "you should login"
    if(sessionUser.isEmpty) {
        Global.error(message)
        throw new RedirectException("/login", message);
    }
}

Now in my test, I created an object with this trait, and test if the Global.error() is equal to RequireLogin.message.

try {
    new Object with RequireLogin
} catch {
    case _: RedirectException =>
}
Global.error should be === RequireLogin.message // !!! can't be compiled

But it can't be compiled.

Is there any way to get the constant from a trait? Or how to refactor my code to make it better?

Upvotes: 3

Views: 3241

Answers (1)

fresskoma
fresskoma

Reputation: 25781

What comes to mind is to define a companion object holding the constant:

object RequireLogin {
    val message = "you should login"
}

Not sure if this is what you're looking for, but I don't think you'll be able to get the value out of the trait itself without using reflection.

Upvotes: 6

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