This class isn't meant to be directly used. Instead you define
validators thru static variables in your {@link Model}. Example:
class Person extends Activerecord\Model {
static $validatesLengthOf = array(
array('name', 'within' => array(30,100),
array('state', 'is' => 2)
);
}
$person = new Person();
$person->name = 'Tito';
$person->state = 'this is not two characters';
if (!$person->is_valid())
print_r($person->errors);