creating a new instance of a type in scala

Question

If I have a class C defined as

class C[A]

is there any way to create a new instance of A within C? Something like

Answer 1

You can demand an implicit parameter, like so:

class A[T](implicit newT : T) { 
  val t = newT 
} 

All you need then is to have an implicit factory of the desired type in scope when you instanciate A, e.g. the following works:

implicit def newSeq[T] = Seq[T]()                
val a = new A[Seq[String]]                            

As shown by:

scala> a.t
res22: Seq[String] = List()