Book Image

Scala Design Patterns

By : Ivan Nikolov
Book Image

Scala Design Patterns

By: Ivan Nikolov

Overview of this book

Scala has become increasingly popular in many different IT sectors. The language is exceptionally feature-rich which helps developers write less code and get faster results. Design patterns make developer’s lives easier by helping them write great software that is easy to maintain, runs efficiently and is valuable to the company or people concerned. You will learn about the various features of Scala and be able to apply well-known, industry-proven design patterns in your work. The book starts off by focusing on some of the most interesting features of Scala while using practical real-world examples. We will also cover the popular "Gang of Four" design patterns and show you how to incorporate functional patterns effectively. By the end of this book, you will have enough knowledge and understanding to quickly assess problems and come up with elegant solutions.
Table of Contents (20 chapters)
Scala Design Patterns
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Preface
Index

Polymorphism


Polymorphism is something every developer who has done some object-oriented programming knows about.

Note

Polymorphism helps us to write generic code that can be reused and applied to a variety of types.

It is important to know that there are different types of polymorphism out there, and we will be looking at them in this section.

Subtype polymorphism

This is the polymorphism every developer knows about, and it's related to overriding methods in concrete class implementations. Consider the following simple hierarchy:

abstract class Item {
  def pack: String
}

class Fruit extends Item {
  override def pack: String = "I'm a fruit and I'm packed in a bag."
}

class Drink extends Item {
  override def pack: String = "I'm a drink and I'm packed in a bottle."
}

Let's now have a shopping basket of items and call pack for each of them:

object SubtypePolymorphismExample {
  def main(args: Array[String]): Unit = {
    val shoppingBasket: List[Item] = List(
      new Fruit,
      new Drink
...