Functions and Methods

Named Arguments

Call a method by naming the parameters.

named-arguments Named arguments make a call read like a small label-value list.

Named Arguments

price
NamedArguments.scala
Replay: real traced execution (multi-file project)
object Main {
  def totalCost(price: Int, quantity: Int): Int = {
    price * quantity
  }

  def main(args: Array[String]): Unit = {
    val price = 12
    val quantity = 2
    val total = totalCost(quantity = quantity, price = price)

    println("price=" + price)
    println("quantity=" + quantity)
    println("total=" + total)
  }
}

object Main {
  def totalCost(price: Int, quantity: Int): Int = {
    price * quantity
  }

  def main(args: Array[String]): Unit = {
    val price = 8
    val quantity = 2
    val total = totalCost(quantity = quantity, price = price)

    println("price=" + price)
    println("quantity=" + quantity)
    println("total=" + total)
  }
}

object Main {
  def totalCost(price: Int, quantity: Int): Int = {
    price * quantity
  }

  def main(args: Array[String]): Unit = {
    val price = 20
    val quantity = 2
    val total = totalCost(quantity = quantity, price = price)

    println("price=" + price)
    println("quantity=" + quantity)
    println("total=" + total)
  }
}

  1. price ← 12, quantity ← 2

    6def main(args: Array[String]): Unit = {7  val price→ 12 = 12 //@price=8, 208  val quantity→ 2 = 29  val total = totalCost(quantity = quantity2, price = price12)1011  println("price=" + price)

  2. def totalCost(price: Int, quantity: Int): Int =

    1object Main {2  def totalCost(price12: Int, quantity2: Int): Int = {3    price12 * quantity24  }

  3. total ← 24, quantity ← 2, price ← 12

    8    val quantity = 29    val total→ 24 = totalCost(quantity→ 2 = quantity, price→ 12 = price)1011    println("price=" + price12)12    println("quantity=" + quantity2)13    println("total=" + total24)14  }15}
    outputprice=12
quantity=2
total=24

  1. price ← 8, quantity ← 2

    6def main(args: Array[String]): Unit = {7  val price→ 8 = 88  val quantity→ 2 = 29  val total = totalCost(quantity = quantity2, price = price8)1011  println("price=" + price)

  2. def totalCost(price: Int, quantity: Int): Int =

    1object Main {2  def totalCost(price8: Int, quantity2: Int): Int = {3    price8 * quantity24  }

  3. total ← 16, quantity ← 2, price ← 8

    8    val quantity = 29    val total→ 16 = totalCost(quantity→ 2 = quantity, price→ 8 = price)1011    println("price=" + price8)12    println("quantity=" + quantity2)13    println("total=" + total16)14  }15}
    outputprice=8
quantity=2
total=16

  1. price ← 20, quantity ← 2

    6def main(args: Array[String]): Unit = {7  val price→ 20 = 208  val quantity→ 2 = 29  val total = totalCost(quantity = quantity2, price = price20)1011  println("price=" + price)

  2. def totalCost(price: Int, quantity: Int): Int =

    1object Main {2  def totalCost(price20: Int, quantity2: Int): Int = {3    price20 * quantity24  }

  3. total ← 40, quantity ← 2, price ← 20

    8    val quantity = 29    val total→ 40 = totalCost(quantity→ 2 = quantity, price→ 20 = price)1011    println("price=" + price20)12    println("quantity=" + quantity2)13    println("total=" + total40)14  }15}
    outputprice=20
quantity=2
total=40