CODEWITHSUNDEEP
scala
Sida Zhou
Sida Zhou

Reputation: 3715

scala how to call overloaded method with correct signature

Using scala 2.10, in scala REPL. I have two definitions of myf, which is overloaded using different argument type. But when I call myf（line 7), it calls def myf(data:List[Int]) instead of def myf(data:List[String]). Despite that the argument itself is of type dataString:List[String].

How do I call myf(data:List[String]) inside myf(data:List[Int]) ?

I tried to handle type erasure with (implicit d: DummyImplicit) as shown in here

def myf(data:List[String]) : Unit = {
    data.foreach(println)
}

def myf(data:List[Int])(implicit d: DummyImplicit) : Unit = {
    val dataString:List[String] = data.map(_ + 1000).map(_.toString)     // do something else before toString
    myf(dataString:List[String])      // want to call myf(data:List[String]), does not want to call myf(data:List[Int])
}

val d:List[Int] = List(1,2,3)
myf(d)

Errors to:

Name: Compile Error
Message: <console>:50: error: type mismatch;
 found   : List[String]
 required: List[Int]
           myf(dataString:List[String])      // want to call myf(data:List[String]), does not want to call myf(data:List[Int])

Upvotes: 0

Views: 87

Answers (1)

jwvh
jwvh

Reputation: 51271

Here's a REPL session that runs your code.

ShellPrompt> scala  #a fresh REPL session
Welcome to Scala 2.12.7 (OpenJDK 64-Bit Server VM, Java 11.0.2).
Type in expressions for evaluation. Or try :help.

scala> :paste
// Entering paste mode (ctrl-D to finish)

def myf(data:List[String]) : Unit = {
    data.foreach(println)
}

def myf(data:List[Int])(implicit d: DummyImplicit) : Unit = {
    val dataString:List[String] = data.map(_ + 1000).map(_.toString)     // do something else before toString
    myf(dataString:List[String])      // want to call myf(data:List[String]), does not want to call myf(data:List[Int])
}

val d:List[Int] = List(1,2,3)
myf(d)

// Exiting paste mode, now interpreting.

1001
1002
1003
myf: (data: List[String])Unit <and> (data: List[Int])(implicit d: DummyImplicit)Unit
myf: (data: List[String])Unit <and> (data: List[Int])(implicit d: DummyImplicit)Unit
d: List[Int] = List(1, 2, 3)

Here's a file-compile demonstration.

ShellPrompt> cat so.sc
object SO {
  def myf(data:List[String]) : Unit = {
    data.foreach(println)
  }

  def myf(data:List[Int])(implicit d: DummyImplicit) : Unit = {
    val dataString:List[String] = data.map(_ + 1000).map(_.toString)
    myf(dataString:List[String])
  }

  def main(args:Array[String]): Unit = {
    val d:List[Int] = List(1,2,3)
    myf(d)
  }
}
ShellPrompt> scalac so.sc -deprecation -explaintypes -feature -unchecked -Xlint -Ypartial-unification
ShellPrompt> scala SO
1001
1002
1003
ShellPrompt>

Upvotes: 1

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