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Flyweight in Scala
/*
run as a script using `scala flyweight.scala`
expected output:
Serving CoffeeFlavour(Espresso) to table 121
Serving CoffeeFlavour(Cappuccino) to table 121
Serving CoffeeFlavour(Frappe) to table 552
Serving CoffeeFlavour(Espresso) to table 96
Serving CoffeeFlavour(Cappuccino) to table 3
Serving CoffeeFlavour(Espresso) to table 3
Serving CoffeeFlavour(Frappe) to table 3
Serving CoffeeFlavour(Cappuccino) to table 97
Serving CoffeeFlavour(Frappe) to table 897
Serving CoffeeFlavour(Espresso) to table 1
Serving CoffeeFlavour(Frappe) to table 1
Serving CoffeeFlavour(Cappuccino) to table 2
total CoffeeFlavour objects made: 3
*/
class CoffeeFlavour(val name: String){
override def toString = s"CoffeeFlavour($name)"
}
object CoffeeFlavour {
import scala.collection.mutable.Map
private val cache = Map.empty[String, CoffeeFlavour]
def apply(name: String): CoffeeFlavour =
cache.getOrElseUpdate(name, new CoffeeFlavour(name))
def totalCoffeeFlavoursMade = cache.size
}
case class Order(tableNumber: Int, flavour: CoffeeFlavour){
def serve: Unit =
println(s"Serving $flavour to table $tableNumber")
}
object CoffeeShop {
var orders = List.empty[Order]
def takeOrder(flavourName: String, table: Int) {
val flavour = CoffeeFlavour(flavourName)
val order = Order(table, flavour)
orders = order :: orders
}
def service: Unit = orders.foreach(_.serve)
def report =
s"total CoffeeFlavour objects made: ${CoffeeFlavour.totalCoffeeFlavoursMade}"
}
CoffeeShop.takeOrder("Cappuccino", 2)
CoffeeShop.takeOrder("Frappe", 1)
CoffeeShop.takeOrder("Espresso", 1)
CoffeeShop.takeOrder("Frappe", 897)
CoffeeShop.takeOrder("Cappuccino", 97)
CoffeeShop.takeOrder("Frappe", 3)
CoffeeShop.takeOrder("Espresso", 3)
CoffeeShop.takeOrder("Cappuccino", 3)
CoffeeShop.takeOrder("Espresso", 96)
CoffeeShop.takeOrder("Frappe", 552)
CoffeeShop.takeOrder("Cappuccino", 121)
CoffeeShop.takeOrder("Espresso", 121)
CoffeeShop.service
println(CoffeeShop.report)
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