问基于类型检查来确定状态是一种代码味道吗？

EN

class Person {

    // many types of glasses available
    protected $glasses;

    public function putOnBoots ()
    {
        // does this type check smell?
        if ($this->glasses instanceof SunGlasses) {
            trigger_error('never wear boots with sunglasses');
            return false;
        }
        // [...] put on boots
        return true;
    }

    public function lookAtStuff ($stuff)
    {
        // glasses provides polymorphic behavior here
        return $this->glasses->filter($stuff);
    }

}