In Scala how can I advise my own methods?

Question

I want to do this:

trait Renderable {
    def render: String
}

trait Parens extends Renderable {
    abstract override def render = \"(\" + super.render + \")\"         


        

Answer 1

How about separating the presentation logic (render) and the actual contents (value)?

trait Renderable {
  def value : String
  def render = value // default presentation logic, simple rendering.
}

trait Parens extends Renderable {
  override def render :String = "(" + value + ")" // parens rendering.
}

object Foo extends Parens {
  def value = "Hello"
}

println(Foo.render) // prints '(Hello)'

---

Edit

Found a way you can do pretty much what you wanted, check it out:

trait Renderable {
  def render: String
}

trait Parens extends Renderable {
  abstract override def render = "(" + super.render + ")"
}

class Foo extends Renderable {
  def render = "Hello"
}

val foo = new Foo with Parens
println(foo.render)

You can't use an object since you need to implement the trait at creation time, but if you can control the instance creation then this might work :).

I'm pretty sure it's not possible to do it otherwise (someone please correct me if I'm wrong)