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tobywestontobyweston
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pattern matching from chapter 18
1 parent 98b5d26 commit d104f7c

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Lines changed: 145 additions & 128 deletions

‎src/main/scala/s4j/scala/chatper18/BasicConstructorPatternExample.scala‎

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package s4j.scala.chatper18
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object BasicConstructorPatternExample extends App {
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val hero = new SuperHero("Batman", "Bruce Wayne", List("Intellect", "Speed", "Agility", "Strength"))
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hero match {
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case SuperHero(_, "Bruce Wayne", _) => println("I'm Batman!")
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case SuperHero(_, _, _) => println("I'm Batman!")
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case _ => println("I'm a civilian")
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}
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}

‎src/main/scala/s4j/scala/chatper18/Customer.scala‎

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package s4j.scala.chatper18
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class Customer(val name: String, val address: String) {
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var yearsACustomer: Int = 0
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}
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object Customer {
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def unapply(customer: Customer): Option[(String, String)] = Some((customer.name, customer.address))
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}

‎src/main/scala/s4j/scala/chatper18/Discount.scala‎

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package s4j.scala.chatper18
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case class Discount(value: Double)

‎src/main/scala/s4j/scala/chatper18/ExtractorExample.scala‎

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package s4j.scala.chatper18
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import s4j.scala.chatper18.Extractors.{DiscountExtractor, UrlExtractor, YearsOfCustom}
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object ExtractorExample extends App {
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val today = ""
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val customer = new Customer("Bob", "1 Church street")
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customer match {
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case Customer(name, address) => println(name + " " + address)
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}
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customer.yearsACustomer = 3
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val discount = customer match {
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case YearsOfCustom(years) if years >= 5 => Discount(0.5)
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case YearsOfCustom(years) if years >= 2 => Discount(0.2)
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case YearsOfCustom(years) if years >= 1 => Discount(0.1)
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case _ if blackFriday(today) => Discount(0)
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case _ => Discount(0)
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}
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println(discount)
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val discount2 = customer match {
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case DiscountExtractor(discount) => discount
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}
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println(discount2)
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val url = "http://baddotrobot.com" match {
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case UrlExtractor(protocol, host) => println(protocol + " " + host)
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}
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def blackFriday(x: String): Boolean = true
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}

‎src/main/scala/s4j/scala/chatper18/Extractors.scala‎

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package s4j.scala.chatper18
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import java.net.{MalformedURLException, URL}
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object Extractors {
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object YearsOfCustom {
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def unapply(customer: Customer): Option[Int] = Some(customer.yearsACustomer)
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}
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object UrlExtractor {
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def unapply(string: String): Option[(String, String)] = {
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try {
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val url = new URL(string)
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Some((url.getProtocol, url.getHost))
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} catch {
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case _: MalformedURLException => None
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}
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}
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}
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object DiscountExtractor {
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def unapply(customer: Customer): Option[Discount] = {
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if (customer.yearsACustomer >= 5) Some(Discount(0.5))
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else if (customer.yearsACustomer >= 2) Some(Discount(0.2))
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else if (customer.yearsACustomer >= 1) Some(Discount(0.1))
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else None
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}
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}
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}

‎src/main/scala/s4j/scala/chatper18/HeroConstructorPatternExample.scala‎

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package s4j.scala.chatper18
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object HeroConstructorPatternExample extends App {
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val bruce = new SuperHero("Batman", "Bruce Wayne", List("Intellect", "Speed", "Agility", "Strength"))
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val youngBruce = new Person("Bruce Wayne")
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val jane = new Person("Jane Doe")
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def superPowersFor(person: Person) = {
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person match {
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case SuperHero(_, name, powers) => powers
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case _ => List()
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}
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}
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// Example of a constructor pattern
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// What super powers does a person have, if they are in fact a super hero who's alter ego is Bruce Wayne?
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val person = bruce
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println("Bruce has the following powers " + superPowersFor(person))
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println("Young Bruce has the following powers " + superPowersFor(youngBruce))
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println("Jane has the following powers " + superPowersFor(jane))
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}

‎src/main/scala/s4j/scala/chatper18/HeroTypePatternExample.scala‎

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package s4j.scala.chatper18
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object HeroTypePatternExample extends App {
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val batman = new SuperHero("Batman", "Bruce Wayne", List("Intellect", "Speed", "Agility", "Strength"))
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val youngBruce = new Person("Bruce Wayne")
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val jane = new Person("Jane Doe")
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def nameFor(person: Person) = {
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person match {
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case hero: SuperHero => hero.alterEgo
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case person: Person => person.name
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}
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}
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// Example of type check pattern
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// What's an super hero's alter ego?
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println("Batman's Alter ego is " + nameFor(batman))
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println("Young Bruce's Alter ego is " + nameFor(youngBruce))
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println("Jane's Alter ego is " + nameFor(jane))
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}

‎src/main/scala/s4j/scala/chatper18/PatternMatching.scala‎

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package s4j.scala.chatper18
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import java.net.{MalformedURLException, URL}
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object PatternMatchingExamples extends App {
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"value" match {
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case "z" => println("z")
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case a => println(a)
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case _ => ???
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case a => println(a)
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case _ => ???
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}
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// constructor pattern
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Foo("bob", 7) match {
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case Foo(x, 9) => println(x + " 09")
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case Foo(x, _) => println(x)
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case _ => ???
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case _ => ???
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}
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case class Foo(string: String, int: Int) {
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def this(string: String) = this(string, 0)
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}
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}
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class Person(val name: String)
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case class SuperHero(heroName: String, alterEgo: String, powers: List[String]) extends Person(alterEgo)
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object BasicConstructorPatternExample extends App {
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val hero = new SuperHero("Batman", "Bruce Wayne", List("Intellect", "Speed", "Agility", "Strength"))
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hero match {
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case SuperHero(_, "Bruce Wayne", _) => println("I'm Batman!")
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case SuperHero(_, _, _) => println("I'm Batman!")
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case _ => println("I'm a civilian")
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}
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}
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object HeroConstructorPatternExample extends App {
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val bruce = new SuperHero("Batman", "Bruce Wayne", List("Intellect", "Speed", "Agility", "Strength"))
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val youngBruce = new Person("Bruce Wayne")
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val jane = new Person("Jane Doe")
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def superPowersFor(person: Person) = {
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person match {
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case SuperHero(_, name, powers) => powers
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case _ => List()
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}
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}
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// Example of a constructor pattern
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// What super powers does a person have, if they are in fact a super hero who's alter ego is Bruce Wayne?
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val person = bruce
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println("Bruce has the following powers " + superPowersFor(person))
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println("Young Bruce has the following powers " + superPowersFor(youngBruce))
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println("Jane has the following powers " + superPowersFor(jane))
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}
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object HeroTypePatternExample extends App {
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val batman = new SuperHero("Batman", "Bruce Wayne", List("Intellect", "Speed", "Agility", "Strength"))
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val youngBruce = new Person("Bruce Wayne")
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val jane = new Person("Jane Doe")
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def nameFor(person: Person) = {
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person match {
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case hero: SuperHero => hero.alterEgo
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case person: Person => person.name
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}
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}
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// Example of type check pattern
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// What's an super hero's alter ego?
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println("Batman's Alter ego is " + nameFor(batman))
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println("Young Bruce's Alter ego is " + nameFor(youngBruce))
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println("Jane's Alter ego is " + nameFor(jane))
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}
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object ExtractorExample extends App {
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val today = ""
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val customer = new Customer("Bob", "1 Church street")
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customer match {
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case Customer(name, address) => println(name + " " + address)
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}
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customer.yearsACustomer = 3
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val discount = customer match {
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case YearsOfCustom(years) if years >= 5 => Discount(0.5)
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case YearsOfCustom(years) if years >= 2 => Discount(0.2)
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case YearsOfCustom(years) if years >= 1 => Discount(0.1)
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case _ if blackFriday(today) => Discount(0)
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case _ => Discount(0)
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}
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println(discount)
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val discount2 = customer match {
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case DiscountExtractor(d) => d
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}
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println(discount2)
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val url = "http://baddotrobot.com" match {
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case UrlExtractor(protocol, host) => println(protocol + " " + host)
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}
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def blackFriday(x: String): Boolean = true
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}
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class Customer(val name: String, val address: String) {
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var yearsACustomer: Int = 0
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}
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object Customer {
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def unapply(customer: Customer): Option[(String, String)] = Some((customer.name, customer.address))
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}
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object YearsOfCustom {
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def unapply(customer: Customer): Option[Int] = Some(customer.yearsACustomer)
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}
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object DiscountExtractor {
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def unapply(customer: Customer): Option[Discount] = {
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if (customer.yearsACustomer >= 5) Some(Discount(0.5))
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else if (customer.yearsACustomer >= 2) Some(Discount(0.2))
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else if (customer.yearsACustomer >= 1) Some(Discount(0.1))
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else None
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}
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}
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object UrlExtractor {
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def unapply(string: String): Option[(String, String)] = {
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try {
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val url = new URL(string)
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Some((url.getProtocol, url.getHost))
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} catch {
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case _: MalformedURLException => None
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}
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}
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}
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case class Discount(value: Double)

‎src/main/scala/s4j/scala/chatper18/Person.scala‎

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package s4j.scala.chatper18
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class Person(val name: String)

‎src/main/scala/s4j/scala/chatper18/SuperHero.scala‎

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package s4j.scala.chatper18
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case class SuperHero(heroName: String, alterEgo: String, powers: List[String]) extends Person(alterEgo)

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