gistfile1.scala

trait Page
trait PageData
    
trait PageOperation {
  type P <: Page
}

trait PageComponent {
  self: PageOperation => 

  protected var page:P = _
  protected var pageData:PageData = _
  def initialise(page0:P, pageData0:PageData) {
    page = page0
    pageData = pageData0    
  }
}

trait AhoyPageOperation extends PageOperation {
  type P = AhoyPage
}

class AhoyPage extends Page    

object MyPageComponent extends PageComponent with AhoyPageOperation {}


trait PageInfo {
  self: PageOperation =>

  def page : P
}

trait AhoyPageInfo extends PageInfo with AhoyPageOperation {
   
   def page = new AhoyPage // for the example
}

object MyApp extends App {
    MyPageComponent.initialise(new AhoyPage, new PageData {})
    //
    MyPageComponent.initialise(new MyPageComponent.P, new PageData {})


    MyPageComponent.initialise((new AhoyPageInfo {}).page , new PageData{})

}