Example : Pattern Matching(Extraction) on Case Classes

scala> //PS:110, 119
scala> //psn > a40 > a60

scala> case class Marks(firstTerm:Int, secondTerm:Int)
defined class Marks

scala> case class Subject(name:String, marks:Marks)
defined class Subject

scala> val phy = Subject("physics", Marks(70, 80))
phy: Subject = Subject(physics,Marks(70,80))

scala> val eng = Subject("english", Marks(75, 85))
eng: Subject = Subject(english,Marks(75,85))

scala> val math = Subject("math", Marks(80, 90))
math: Subject = Subject(math,Marks(80,90))


scala> for { seq <- Seq(phy, eng, math) } {
     |     val result = seq match {
     |         // Note 1 : unapply() method is used for Extraction
     |         //          (whereas apply() is used for creating an Object)
     |         // Note 2 : unapply()(apart from apply()) is also another
     |         //          method that has been created by the Compiler
     |         //          as part of Companion Object
     |         case Subject("physics", Marks(70, _)) => s"Physics : $seq"
     |         case s @ Subject("english", m @ Marks(_, _)) =>
     |                         s"English mark : ${m}"
     |         case Subject(_, _) => s"Others : $seq"
     |     }
     |     println(result)
     | }
Physics : Subject(physics,Marks(70,80))
English mark : Marks(75,85)
Others : Subject(math,Marks(80,90))