CODEWITHSUNDEEP
scala
piyush tripathi
piyush tripathi

Reputation: 117

getting error while trying to use scala extractors without case classes

I'm new to scala and just learning to code . can someone tell me what am i doing wrong here

          class ForExtractor(val i : Int , j:Int){
    //def unapply(i:Int) = true
  }
  object ForExtractor{
    def unapply(i:Int ):Option[(Int , Int)] = if(i>2)Some(1,2) else None
  }
  def extractorTest(obj : ForExtractor) = {
    obj match {
      case ForExtractor(4,2)=> true ;
      case e => false
    }
  }

The error that i see on case line is 

    pattern type is incompatible with expected type ; found:Int ,
    ForExtractor

Upvotes: 1

Views: 47

Answers (1)

Simonlbc
Simonlbc

Reputation: 651

What i can guess is that you want to test whether the val i in your ForExtractor is bigger that 2 or not, and in this case return Some((1,2)) (notice your error here you're returning Some(1,2)).

your unapply method should take as argument a ForExtractor, so in the end the unapply method would look like this:

 def unapply(forex: ForExtractor):Option[(Int , Int)] = 
         if(forex.i > 2)Some((1,2)) else None

then we get:

scala> extractorTest(new ForExtractor(1, 2))
res1: Boolean = false

Upvotes: 1

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