Introspect a Scala class for traits?

Question

Is there an introspection api somewhere in Scala to find the traits a class is implementing ?

For Scala 2.9.2 that is.

Answer 1

Trait in Scala translate to interfaces in Java, so you can use Java's reflection library to find out which traits are implemented. Here is an example:

trait Foo
class Bar extends Foo 

val b = new Bar
b.getClass.getInterfaces.foreach(println)

This prints:

interface Foo
interface scala.ScalaObject

Answer 2

Note that the example Kim Stebel used does not work if the trait is implemented by a superclass. Here is a more general form:

  def implementsInterface(target: Class[_], someInterface: Class[_]): Boolean = {
    val i = target.getInterfaces
    i.foreach((c: Class[_]) => if (c == someInterface) return true)

    val s = target.getSuperclass

    if (s == null) false
    else implementsInterface(s, someInterface)
  }