use scala reflection

[squito]

switch to scala reflection, which will allow sumac to support types like List[Int]. Finally found the key thing required for this:

import scala.reflect.runtime.{universe => ru}
def getType[T: ru.TypeTag](obj: T) = ru.typeTag[T].tpe
class Foo
class Bar extends Foo
val b: Foo = new Bar
scala> getType(b)
res0: reflect.runtime.universe.Type = Foo

scala> b.getClass()
res1: Class[_ <: Foo] = class Bar


class Foo {
  def doStuff() = { 
    this.getClass().getDeclaredField("y")
  }
}

class Bar extends Foo {
  val x: Int = 17
  val y: List[Int] = List(1,2,3)
}


def getRuntimeType[A](item: A) = {
  val mirror = ru.runtimeMirror(this.getClass.getClassLoader)
  mirror.classSymbol(item.getClass).toType
}


val b : Foo = new Bar
scala> getRuntimeType(b).members.collect{case x if x.isTerm => x.asTerm}.filter{_.isGetter}.map{x => x -> x.typeSignature}.toMap
Map(value y -> => scala.List[scala.Int], value x -> => scala.Int)

http://stackoverflow.com/questions/17010237/using-scala-reflection-to-find-most-derived-runtime-type

[squito]

scala reflection won't be thread safe until 2.11
https://issues.scala-lang.org/browse/SI-6240

this is a very real problem -- I ran into it immediately when writing unit tests. At first I just side-stepped it by turning off parallel execution of tests. But I realized, we just can't have Sumac be so unsafe. (even though it is entirely single-threaded, the users code might invoke reflection in another thread at the same time ... and then we're hosed.)

I think this means we have to wait till 2.11