CODESAMPLE

Abstract Factory - Scala

Abstract Factory Scala

The Abstract Factory pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes. It’s a “factory of factories,” allowing you to switch between different “looks and feels” or object sets easily.

This Scala implementation defines traits Button and Checkbox representing product types, and concrete classes for different themes (e.g., WindowsButton, MacOSCheckbox). The GUIFactory trait is the abstract factory, defining methods to create buttons and checkboxes. Concrete factories like WindowsFactory and MacOSFactory implement these methods to return objects specific to their theme. A Client class uses the factory to create a GUI without knowing the concrete classes involved, promoting loose coupling and flexibility. Scala’s traits and case classes make this pattern concise and type-safe.

trait Button {
  def paint(): String
}

trait Checkbox {
  def paint(): String
}

trait GUIFactory {
  def createButton(): Button
  def createCheckbox(): Checkbox
}

case class WindowsButton() extends Button {
  override def paint(): String = "Windows Button"
}

case class MacOSButton() extends Button {
  override def paint(): String = "MacOS Button"
}

case class WindowsCheckbox() extends Checkbox {
  override def paint(): String = "Windows Checkbox"
}

case class MacOSCheckbox() extends Checkbox {
  override def paint(): String = "MacOS Checkbox"
}

case class WindowsFactory() extends GUIFactory {
  override def createButton(): Button = WindowsButton()
  override def createCheckbox(): Checkbox = WindowsCheckbox()
}

case class MacOSFactory() extends GUIFactory {
  override def createButton(): Button = MacOSButton()
  override def createCheckbox(): Checkbox = MacOSCheckbox()
}

object Client {
  def createGUI(factory: GUIFactory): String = {
    val button = factory.createButton()
    val checkbox = factory.createCheckbox()
    s"${button.paint()}, ${checkbox.paint()}"
  }
}

object Main extends App {
  val windowsGUI = Client.createGUI(WindowsFactory())
  println(windowsGUI)

  val macosGUI = Client.createGUI(MacOSFactory())
  println(macosGUI)
}