Is it possible to define a type alias which represent mutliple data types?
package object scala {
type SingleDimension = Double
type MultiDimensionMap = Map[String, Double]
type MultiDimensionList = List[Tuple2[String, Double]]
}
e.g. I need a suptertype lets say DataDimension that represent only above three types. so I can do following:
trait AbstractDataWorker[T] {
def formula(d: Double): T
}
class multiDimensionWorker extends AbstractDataWorker[MultiDimensionMap] {
type T = MultiDimensionMap
override def formula(d: Double): MultiDimensionMap = {
Map[String, Double]()
}
}
class singleDimensionWorker extends AbstractDataWorker[SingleDimension] {
type T = SingleDimension
override def formula(d: Double): SingleDimension = {
2.0
}
}
But following should give compile error. Currently it works.
class stringDimensionWorker extends AbstractDataWorker[String] {
type T = String
override def formula(d: Double): String = {
"hello"
}
}
You can make them real classes extending a single trait instead of type aliases:
sealed trait DimensionLike
case class SingleDimension(value: Double) extends DimensionLike
case class MultiDimensionMap(value: Map[String, Double]) extends DimensionLike
case class MultiDinmensionList(value: List[(String, Double)]) extends DimensionLike
abstract class AbstractDataWorker[T <: DimensionLike] {
def formula(d: Double): T
}
class MultiDimensionWorker extends AbstractDataWorker[MultiDimensionMap] {
// ...
}
Or you can make a typeclass with implicit implementations for those type aliases. Then make AbstractDataWorker an abstract class, and add a context bound for this typeclass to its type argument:
type SingleDimension = Double
type MultiDimensionMap = Map[String, Double]
type MultiDimensionList = List[(String, Double)]
sealed trait IsDimensionLike[T]
object IsDimensionLike {
implicit object singleDimension extends IsDimensionLike[SingleDimension]
implicit object multiDimensionMap extends IsDimensionLike[MultiDimensionMap]
implicit object multiDimensionList extends IsDimensionLike[MultiDimensionList]
}
abstract class AbstractDataWorker[T : IsDimensionLike] {
def formula(d: Double): T
}
class MultiDimensionWorker extends AbstractDataWorker[MultiDimensionMap] {
// ...
}
