Scala example source code file (WrappedProperties.scala)

This example Scala source code file (WrappedProperties.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

accesscontrol, list, nil, none, option, propertiestrait, some, string, t, utilities, wrappedproperties

The WrappedProperties.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2006-2013 LAMP/EPFL
 * @author  Paul Phillips
 */

package scala.tools
package reflect

import scala.util.PropertiesTrait
import java.security.AccessControlException

/** For placing a wrapper function around property functions.
 *  Motivated by places like google app engine throwing exceptions
 *  on property lookups.
 */
trait WrappedProperties extends PropertiesTrait {
  def wrap[T](body: => T): Option[T]

  protected def propCategory   = "wrapped"
  protected def pickJarBasedOn = this.getClass

  override def propIsSet(name: String)               = wrap(super.propIsSet(name)) exists (x => x)
  override def propOrElse(name: String, alt: String) = wrap(super.propOrElse(name, alt)) getOrElse alt
  override def setProp(name: String, value: String)  = wrap(super.setProp(name, value)).orNull
  override def clearProp(name: String)               = wrap(super.clearProp(name)).orNull
  override def envOrElse(name: String, alt: String)  = wrap(super.envOrElse(name, alt)) getOrElse alt
  override def envOrNone(name: String)               = wrap(super.envOrNone(name)).flatten
  override def envOrSome(name: String, alt: Option[String]) = wrap(super.envOrNone(name)).flatten orElse alt

  def systemProperties: List[(String, String)] = {
    import scala.collection.JavaConverters._
    wrap {
      val props = System.getProperties
      // SI-7269 Be careful to avoid `ConcurrentModificationException` if another thread modifies the properties map
      props.stringPropertyNames().asScala.toList.map(k => (k, props.get(k).asInstanceOf[String]))
    } getOrElse Nil
  }
}

object WrappedProperties {
  object AccessControl extends WrappedProperties {
    def wrap[T](body: => T) = try Some(body) catch { case _: AccessControlException => None }
  }
}