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trait User {
def name: String
}
//class FreeUser(name: String, upgradeProbality: Double) extends User
//class PremiumUser(name: String, loaltyPoint: Double) extends User
//val user1 = new FreeUser("John", 0.75)
//println(user1.name) doesn't work
class FreeUser(val name: String, val upgradeProbality: Double) extends User
class PremiumUser(val name: String, val loaltyPoint: Double) extends User
//val user1 = new FreeUser("John", 0.75)
//println(s"Hello ${user1.name}")
// pattern matching
object FreeUser {
def unapply(user: FreeUser): Option[(String, Double)] = Some((user.name, user.upgradeProbality))
}
object PremiumUser {
def unapply(user: PremiumUser): Option[(String, Double)] =
Some(user.name, user.loaltyPoint)
}
val user1: User = new FreeUser("John", 0.75)
val user2: User = new PremiumUser("Rebacca", 120)
def greetUser(user: User): Unit = user match {
case FreeUser(name, _) => println(s"Hello $name")
case PremiumUser(name, _) => println(s"Hello $name, what can I do for you?")
}
greetUser(user1)
greetUser(user2)
List(user1,user2) foreach greetUser
// Boolean extractor
def sendUpgradeSpam(user: FreeUser) = {
val message = s"Hello ${user.name}, congratulations!! You're eleigible for " +
s"our premium services. For more information, pleaes visit our site: http://play/premium"
println(message)
}
def isUpgradeEligible(user: FreeUser): Boolean = {
if (user.upgradeProbality > 0.6) true else false
}
// using a function
def spam(user: FreeUser) = {
if (isUpgradeEligible(user)) println("Yes, Send him an email")
else println("No, Don't spam him")
}
spam(new FreeUser("Joe", 0.4))
// object and pattern matching
object UpgradeEligible {
def unapply(user: FreeUser): Boolean =
if (user.upgradeProbality > 0.6) true else false
}
val user3 = new FreeUser("Joe", 0.4)
/*
user3 match {
case UpgradeEligible() => println("Yes, Send him an email") // if true
case _ => println("No, Don't spam him") // if false
}
*/
def spamEligibleUsers(user: User): Unit = user match {
case freeUser @ UpgradeEligible() => sendUpgradeSpam(freeUser)
case _ => // do nothing
}
spamEligibleUsers(user1)
def makeArray[T: ClassTag](elements: T*) = Array[T](elements: _*)
makeArray(1, 2 ,3, 4)
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