Scala example source code file (t1500.scala)

This example Scala source code file (t1500.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

a, a, annotationchecker, array, b, boolean, interpreter, interpreter, settings, test, test, type, type, typeconstraint

The Scala t1500.scala source code

import scala.tools.nsc._  

object Test {
  
  /**
   *  Type inference overlooks constraints posed by type parameters in annotations on types.
   */
  
  val testCode = <code>
  
    class posingAs[A] extends TypeConstraint
    
    def resolve[A,B](x: A @posingAs[B]): B = x.asInstanceOf[B]
    
    val x = resolve(7: @posingAs[Any])
  
  </code>.text
  
  def main(args: Array[String]) = {
    
    val settings = new Settings()
    settings.classpath.value = System.getProperty("java.class.path")
    val tool = new Interpreter(settings)
    val global = tool.compiler

    import global._
    import definitions._

    object checker extends AnnotationChecker {

      /** Check annotations to decide whether tpe1 <:< tpe2 */
      def annotationsConform(tpe1: Type, tpe2: Type): Boolean = {

        tpe1.annotations.forall(a1 => tpe2.annotations.forall(a2 => a1.atp <:< a2.atp))

      }
    }
    
    global.addAnnotationChecker(checker)
    
    tool.interpret(testCode)
    
  }

}