Question

The following code fails to compile (Output is not of type java.reflect.annotation.Annotation):

class Output(val name : String) extends Annotation

class Block {
  def outputs {
    for {
      method <- this.getClass.getMethods
      val a = method.getAnnotation(classOf[Output])
      if a != null
    } {
      println(a.name)
    }
  }
}

class Arithmetic[T: Numeric](val A: Connector[T], val B: Connector[T]) extends Block {
  @Output("Sum")        def Sum  = new Connector({ A.Value + B.Value })
  @Output("Difference") def Diff = new Connector({ A.Value - B.Value })
  @Output("Multiply")   def Mul  = new Connector({ A.Value * B.Value })
}

Is there any way to achieve runtime reflection on the annotated members?

Answer 1

It seems there is no way to achieve this in Scala (yet), and thus we should resort to using a Java class as such:

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Output {
    public String value();
}