thing_and_client.scala

//A trait with a function 'do' 
trait Thingy {
  def do : String
}

//A global object that implements Thingy
object Thingy extends Thingy{
  def do = "thing"
}


//Approach 1: Wiring a global object 
//Pros: less code
//Cons: hardwired dependency - makes it harder to isolate and test
class ClientOne {
  def do = Thingy.do
}


//Approach 2: Don't wire in the trait instead declare the depenency
//Pros: allows isolation testability
//Cons: requires more code for final wiring
trait CientTwo {
  def thingy : Thingy
  def do = thingy.do
}
//Approach 2 cont.. then when wiring up the app assign the dependency
new ClientTwo{
  def thingy = Thingy
}