What a work in Zend2 !!! It is getting great, but what about final classes and object constants in class definition?

I need to do something like this:

class EnumException extends Exception{ }

final class Car {
    //private
    const _ferrari = 0;
    const _porsche = 1;
    const _corvette = 2;

    //private
    const _last_value = 2;

    //public
    const ferrari = new Car(_ferrari);
    const porsche = new Car(_porsche);
    const corvette = new Car(_corvette);

    private $value;

    protected function __construct($value) {
        if (($value < 0) || ($value > _last_value)) {
            throw new EnumException();
        }
        $this->value = $value;
    }
    public function value() {
        return $this->value;
    }
}

Everything works fine, except the "final" keyword and the "const" initialization with an object.

I think final classes would be a good approach in assuring that a class will not be modified(inherited).

Why can?t objects be assigned to constants ? Is there another way of doing this in Zend2 ?

Thanx,

Cristiano Duarte