waarom classes?

<?php
class User {
	protected $_vacature = null;
	protected $_validator = null;
	public $_user = false;
	public $_userId;
		
	public function __construct() {
		$this->_vacature = new Vacature;
		$this->_validator = new Validator;
		
		$userId = $this->_validator->checkSession(1);
		if(is_numeric($userId)) {
			$this->_user = true;
			$this->_userId = $userId;
		}
	}
?>

<?php
class User {
	protected $_vacature = null;
	protected $_validator = null;
	public $_user = false;
	public $_userId;
 
	public function __construct() {
		$this->_vacature = new Vacature;
		$this->_validator = new Validator;
 
		$userId = $this->_validator->checkSession(1);
		if(is_numeric($userId)) {
			$this->_user = true;
			$this->_userId = $userId;
		}
	}
?>

var topics = Lid.Topics;

var topics = Lid.Topics;

var topics = currentTopic.Category.Topics;

var topics = currentTopic.Category.Topics;

var categories = currentTopic.Category.Parent.Categories;

var categories = currentTopic.Category.Parent.Categories;

select c.* from categorien c, categorien c2, categorien parentC WHERE c2.id = (select categoryId from topics where id = JE_TOPIC_ID_HIER) AND c2.parentCat = parentC.id AND c.parentCat = parentC

select c.* from categorien c, categorien c2, categorien parentC WHERE c2.id = (select categoryId from topics where id = JE_TOPIC_ID_HIER) AND c2.parentCat = parentC.id AND c.parentCat = parentC

class ClsDb
{
    public function insert($insert)
    {
    }

    public function delete($delete)
    {
    }
    //etc.
}

class ClsDb
{
    public function insert($insert)
    {
    }
 
    public function delete($delete)
    {
    }
    //etc.
}

    public function query($query)
    {
    }

public function query($query)
    {
    }

    public function insert($insert)
    {
        return $this->query($insert);
    }

public function insert($insert)
    {
        return $this->query($insert);
    }

    private $queries = array();

private $queries = array();