Restrictions in trait mixing

Question

I want to have classes that can mix only specified traits:

class Peter extends Human with Lawful with Evil
class Mag extends Elf with Chaotic with Neutral

Is in Scala a way to do this?

UPD:

trait Law
trait Lawful extends Law
trait LNeutral extends Law
trait Chaotic extends Law

trait Moral
trait Good extends Moral
trait Neutral extends Moral
trait Evil extends Moral

class Hero .........
class Homer extends Hero with Chaotic with Good

I want to define a Hero class in a way that constrains the client programmer to mix specific traits (Lawful/LNeutral/Chaotic and Good/Neutral/Evil) if he extends the Hero class. And I want to find some other possibilities to restrict/constrain client code like this.

Answer 1

Perhaps you're looking for restricting self-type declarations. E.g.:

class Human
trait Lawful
trait Lawless

class NiceGuy
extends Human
{
  this: Lawful =>
}

class BadGuy
extends Human
{
  this: Lawless =>
}


scala> class SuperHero extends NiceGuy
<console>:7: error: illegal inheritance;
 self-type SuperHero does not conform to NiceGuy's selftype NiceGuy with Lawful
       class SuperHero extends NiceGuy
                               ^

scala> class SuperHero extends NiceGuy with Lawful
defined class SuperHero

scala> class SuperVillain extends BadGuy
<console>:7: error: illegal inheritance;
 self-type SuperVillain does not conform to BadGuy's selftype BadGuy with Lawless
       class SuperVillain extends BadGuy
                                  ^

scala> class SuperVillain extends BadGuy with Lawless
defined class SuperVillain