How to get the class of a singleton object at compile time?

Question

Consider something like this:

object Singleton

val cls: Class[Singleton] = ???

What do I have to write instead of ????

I tried classOf[Singleton], classOf[Singleton.type], Singleton.type, but nothing worked.

(I know of course about getClass, the runtime version of classOf, but that's not what I'm asking.)

score 7 · Accepted Answer · edited May 23 '17 at 12:08

7

Here a solution, but it's not pretty ...

object Singleton

val cls : Class[Singleton] = Singleton.getClass.asInstanceOf[Class[Singleton]]

Edit: completed the solution after reading another question/answer: Scala equivalent of Java java.lang.Class<T> Object

Note1: type erasure would prevent this from being particularly useful, e.g. in pattern matching. See referenced question/answer, above, for a good explanation

Note2: the scala -explaintypes flag is quite handy in understanding type errors.

HTH

edited May 23 '17 at 12:08

Community

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answered May 25 '11 at 00:15

laher

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`.asInstanceOf[AnyRef]` does not appear to be needed for this to work. – axel22 May 25 '11 at 07:17

score 4 · Answer 2 · answered May 25 '11 at 13:27

4

You are not alone with this problem. The answer is: There is currently no way to avoid a Singleton.getClass. See this comment for more information why classOf[Singleton] does not work

answered May 25 '11 at 13:27

kiritsuku

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How to get the class of a singleton object at compile time?

2 Answers2