gistfile1.mkd

== Scala 2.7.5

scalac shapes.scala shapes-actor.scala
scala shapes-actor-script.scala // it works

== Scala 2.8.0

scalac shapes.scala shapes-actor.scala
scala shapes-actor-script.scala // NOT works
scala -cp . shapes-actor-script.scala // NOT works

> /Users/ihower/scala/code-examples/IntroducingScala/shapes-actor-script.scala:3: error: not found: value shapes
> import shapes._
>      ^
> one error found

scala -cp ~/scala/code-examples/IntroducingScala shapes-actor-script.scala // it works 需要加上絕對路徑

shapes-actor-script.scala

// code-examples/IntroducingScala/shapes-actor-script.scala

import shapes._

ShapeDrawingActor.start()

ShapeDrawingActor ! new Circle(new Point(0.0,0.0), 1.0)
ShapeDrawingActor ! new Rectangle(new Point(0.0,0.0), 2, 5)
ShapeDrawingActor ! new Triangle(new Point(0.0,0.0),
                                 new Point(1.0,0.0),
                                 new Point(0.0,1.0))
ShapeDrawingActor ! 3.14159
 
ShapeDrawingActor ! "exit"

shapes-actor.scala

// code-examples/IntroducingScala/shapes-actor.scala

package shapes {
  import scala.actors._
  import scala.actors.Actor._

  object ShapeDrawingActor extends Actor {
    def act() {
      loop {
        receive {
          case s: Shape => s.draw()
          case "exit"   => println("exiting..."); exit
          case x: Any   => println("Error: Unknown message! " + x)
        }
      }
    }
  }
}

shapes.scala

// code-examples/IntroducingScala/shapes.scala

package shapes {  
  class Point(val x: Double, val y: Double) {
    override def toString() = "Point(" + x + "," + y + ")"
  }

  abstract class Shape() { 
    def draw(): Unit
  }
  
  class Circle(val center: Point, val radius: Double) extends Shape {
    def draw() = println("Circle.draw: " + this)
    override def toString() = "Circle(" + center + "," + radius + ")"
  }
  
  class Rectangle(val lowerLeft: Point, val height: Double, val width: Double)
        extends Shape {
    def draw() = println("Rectangle.draw: " + this)
    override def toString() = 
      "Rectangle(" + lowerLeft + "," + height + "," + width + ")"
  }

  class Triangle(val point1: Point, val point2: Point, val point3: Point) 
        extends Shape {
    def draw() = println("Triangle.draw: " + this)
    override def toString() = 
      "Triangle(" + point1 + "," + point2 + "," + point3 + ")"
  }
}