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Scala example source code file (AbstractOrMissingHandler.scala)

This example Scala source code file (AbstractOrMissingHandler.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

abstractmethoderror, abstractormissinghandler, abstractormissinghandler, failed, failed, missingrequirementerror, missingrequirementerror, noclassdeffounderror, nosuchmethoderror, nosuchmethoderror, otherwise, partialfunction, t, throwable

The Scala AbstractOrMissingHandler.scala source code

/* NSC -- new Scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author  Paul Phillips
 */

package scala.tools.nsc
package interpreter

class AbstractOrMissingHandler[T](onError: String => Unit, value: T) extends PartialFunction[Throwable, T] {
  def isDefinedAt(t: Throwable) = t match {
    case _: AbstractMethodError     => true
    case _: NoSuchMethodError       => true
    case _: MissingRequirementError => true
    case _: NoClassDefFoundError    => true
    case _                          => false
  }
  def apply(t: Throwable) = t match {
    case x @ (_: AbstractMethodError | _: NoSuchMethodError | _: NoClassDefFoundError) =>
      onError("""
        |Failed to initialize compiler: %s.
        |This is most often remedied by a full clean and recompile.
        |Otherwise, your classpath may continue bytecode compiled by
        |different and incompatible versions of scala.
        |""".stripMargin.format(x.getClass.getName split '.' last)
      )
      x.printStackTrace()
      value
    case x: MissingRequirementError =>
      onError("""
        |Failed to initialize compiler: %s not found.
        |** Note that as of 2.8 scala does not assume use of the java classpath.
        |** For the old behavior pass -usejavacp to scala, or if using a Settings
        |** object programatically, settings.usejavacp.value = true.""".stripMargin.format(x.req)
      )
      value
  }
}

object AbstractOrMissingHandler {
  def apply[T]() = new AbstractOrMissingHandler[T](Console println _, null.asInstanceOf[T])
}

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