ケーキパターンは、この問題を元の形で解決しません。あなたはそれに対処する方法がseveral choicesあります。私が好む解決策は、適切なパラメータを持つコンストラクタを呼び出すことによって各 "ロボット脚"を作成することです。codeは単語よりも優れています。
は、私が先に引用答えは、より読みやすいと思いますが、あなたはすでにヨナス例に精通している場合は、ここであなたが向きでウォーマー、設定を行いたい方法です:
// =======================
// service interfaces
trait OnOffDeviceComponent {
val onOff: OnOffDevice
trait OnOffDevice {
def on: Unit
def off: Unit
}
}
trait SensorDeviceComponent {
val sensor: SensorDevice
trait SensorDevice {
def isCoffeePresent: Boolean
}
}
// =======================
// service implementations
trait OnOffDeviceComponentImpl extends OnOffDeviceComponent {
class Heater extends OnOffDevice {
def on = println("heater.on")
def off = println("heater.off")
}
}
trait SensorDeviceComponentImpl extends SensorDeviceComponent {
class PotSensor extends SensorDevice {
def isCoffeePresent = true
}
}
// =======================
// service declaring two dependencies that it wants injected
trait WarmerComponentImpl {
this: SensorDeviceComponent with OnOffDeviceComponent =>
// Note: Warmer's orientation is injected by constructor.
// In the original Cake some mixed-in val/def would be used
class Warmer(rightSide: Boolean) {
def isRightSide = rightSide
def trigger = {
if (sensor.isCoffeePresent) onOff.on
else onOff.off
}
}
}
// =======================
// instantiate the services in a module
object ComponentRegistry extends
OnOffDeviceComponentImpl with
SensorDeviceComponentImpl with
WarmerComponentImpl {
val onOff = new Heater
val sensor = new PotSensor
// Note: now we need to parametrize each particular Warmer
// with its desired orientation
val leftWarmer = new Warmer(rightSide = false)
val rightWarmer = new Warmer(rightSide = true)
}
// =======================
val leftWarmer = ComponentRegistry.leftWarmer
leftWarmer.trigger