New Cake pattern (from @etorreborre)

gistfile1.scala

trait Cake {
  type Config
  def config: Config
}

trait FooConfig {
  // ...
}

trait FooComponent extends Cake {
  type Config <: FooConfig
  
  def foo: Foo = ...
  
  trait Foo {
    // do something here
  }
}

trait BarConfig {
  // ...
}

trait BarComponent extends Cake {
  type Config <: BarConfig
  
  type Bar
  def bar: Bar
}

trait BazBar {
  // ...
}

trait BazComponent extends BarComponent {
  type Bar <: BazBar
  
  def baz: Baz = ...
  
  trait Baz {
    // something that requires bar: BazBar
  }
}

trait BinBarComponent extends BazComponent {
  def bar: Bar = ...
  
  trait Bar extends BazBar {
    // ...
  }
}


def main(args: Array[String]) {
  val cake = new FooComponent with with BazComponent with BinBarComponent {
    def config = new BarConfig with FooConfig {
      // ...
    }
  }
  
  // do something with cake
}