Re: Type problem

Sorry, I guess I still didn't explain myself. Let me try using more concrete terms.
A is Mapper. B is a supertype of several mapper classes. It's type parameter must be a subclass of B, not A. Also it has a self type of this: T.
C is my MappedOneToMany class. It is _declared_ to take a type parameter derived from _A_. But I need an instance of C that can be used with any B derivative. I can't figure out how to pass B as a type parameter to C so that the instance can contain derivatives of, without getting compiler errors. The problem is that for starters, extends C[B] gives the error that B takes type parameters. But _ doesn't satisfy the compiler, and of course B[_ <: B] doesn't solve the problem
(This leads to a lift question, but even if its answer is no the above question still stands in theory. Must a mapper's type parameter be the concrete subclasses's type, or can you define a nonparameterized base type for a group of mappers?)

-------------------------------------
David Pollak<feeder.of.the.bears@...> wrote:

trait A[T <: A[T]]

trait B[T <: A[T]] extends A[T] {
  def name: String
}

trait C[T <: B[_]] {
  def doSomething(p: T) {
    println(p.name)
  }

  def anotherB(b: B[_]) = {
    b.name
  }
}

class AC extends A[AC]

class BC extends AC with B[AC] {
  def name = "Frog"
}

class BC2 extends AC with B[AC] {
  def name = "BC2"
}

class CC extends C[BC] {
}

val cc = new CC
val bc = new BC
val bc2 = new BC2

println(cc.anotherB(bc2))

On Sun, Jul 5, 2009 at 9:12 PM, Naftoli Gugenhem <naftoligug@...>wrote:



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