Use AnyVal

gistfile1.txt

class ImplicitString(val c : C[String]) extends AnyVal {
  def foo(): Unit = Console.println(c.t.toUpperCase())
}

class ImplicitInt(val c: C[Int]) extends AnyVal {
  def foo(): Unit = Console.println(c.t)
}

object Main {
  implicit def cstrImpl(c: C[String]) = new ImplicitString(c)
  implicit def cintImpl(c: C[Int]) = new ImplicitInt(c)
  def main(args: Array[String]) {

    val cstr = new C[String]("hw")
    val cint = new C[Int](0)

    cstr.foo()
    cint.foo()
  }
}