Bridge.scala

// http://en.wikipedia.org/wiki/Bridge_pattern

trait DrawingAPI {
  def drawCircle(x:Double, y: Double, radius:Double)
}

class DrawingAPI1 extends DrawingAPI {
  override def drawCircle(x: Double, y: Double, radius: Double) = {
    printf("API1.circle at %f:%f radius %f\n", x, y, radius)
  }
}

class DrawingAPI2 extends DrawingAPI {
  override def drawCircle(x: Double, y: Double, radius: Double) = {
    printf("API2.circle at %f:%f radius %f\n", x, y, radius)
  }
}

abstract class Shape(drawingAPI: DrawingAPI) {
  def draw
  def resizeByPercentage(pct: Double)
}

class CircleShape(x: Double, y: Double, radius: Double, drawingAPI: DrawingAPI)
extends Shape(drawingAPI) {
  var _x: Double = x
  var _y: Double = y
  var _radius: Double = radius

  override def draw = drawingAPI.drawCircle(_x, _y, _radius)
  override def resizeByPercentage(pct: Double) = _radius *= pct
}

object BridgeSample {
  def main(args: Array[String]) = {
    var shapes = List(
      new CircleShape(1,2,3, new DrawingAPI1()),
      new CircleShape(5,7,11, new DrawingAPI2())
    )

    shapes.foreach ((s:Shape) => {
      s.resizeByPercentage(2.5)
      s.draw
    })
  }
}  

BridgeSample.main(Array())