Given:
case class Thing(a:Int, b:String, c:Double)
val v = Vector(1, "str", 7.3)
I want something that will magically create:
Thing(1, "str", 7.3)
Does such a thing exist (for arbitrary size Things)?
My first time dipping my toes into the 2.10 experimental reflection facilities. So mostly following this outline http://docs.scala-lang.org/overviews/reflection/overview.html, I came up with this:
import scala.reflect.runtime.{universe=>ru}
case class Thing(a: Int, b: String, c: Double)
object Test {
def main(args: Array[String]) {
val v = Vector(1, "str", 7.3)
val thing: Thing = Ref.runtimeCtor[Thing](v)
println(thing) // prints: Thing(1,str,7.3)
}
}
object Ref {
def runtimeCtor[T: ru.TypeTag](args: Seq[Any]): T = {
val typeTag = ru.typeTag[T]
val runtimeMirror = ru.runtimeMirror(getClass.getClassLoader)
val classSymbol = typeTag.tpe.typeSymbol.asClass
val classMirror = runtimeMirror.reflectClass(classSymbol)
val constructorSymbol = typeTag.tpe.declaration(ru.nme.CONSTRUCTOR).asMethod
val constructorMirrror = classMirror.reflectConstructor(constructorSymbol)
constructorMirrror(args: _*).asInstanceOf[T]
}
}
Note that when I had the case class inside the main method, this did not compile. I don't know if type tags can only be generated for non-inner case classes.