Scala example source code file (ObservableSet.scala)

This example Scala source code file (ObservableSet.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

a, include, observables, observableset, pub, publisher, remove, reset, undoable, unit

The ObservableSet.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |                                         **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */



package scala
package collection
package mutable

import script._

/** This class is typically used as a mixin. It adds a subscription
 *  mechanism to the `Set` class into which this abstract
 *  class is mixed in. Class `ObservableSet` publishes
 *  events of the type `Message`.
 *
 *  @author  Matthias Zenger
 *  @version 1.0, 08/07/2003
 *  @since   1
 */
@deprecated("Observables are deprecated because scripting is deprecated.", "2.11.0")
trait ObservableSet[A] extends Set[A] with Publisher[Message[A] with Undoable]
{

  type Pub <: ObservableSet[A]

  abstract override def +=(elem: A): this.type = {
    if (!contains(elem)) {
      super.+=(elem)
      publish(new Include(elem) with Undoable { def undo = -=(elem) })
    }
    this
  }

  abstract override def -=(elem: A): this.type = {
    if (contains(elem)) {
      super.-=(elem)
      publish(new Remove(elem) with Undoable { def undo = +=(elem) })
    }
    this
  }

  abstract override def clear(): Unit = {
    super.clear()
    publish(new Reset with Undoable {
      def undo(): Unit = throw new UnsupportedOperationException("cannot undo")
    })
  }
}