PHP5.3的发布修复了5.2版本中所有的bug,同时增加了几个有意思的功能，如namespace,closures，namespace个人觉得不是很喜欢，但是Closure很好玩，以下代码摘自php.net

<?php // A basic shopping cart which contains a list of added products // and the quantity of each product. Includes a method which // calculates the total price of the items in the cart using a // closure as a callback. class Cart {     const PRICE_BUTTER  = 1.00;     const PRICE_MILK    = 3.00;     const PRICE_EGGS    = 6.95;     protected   $products = array();          public function add($product, $quantity)     {         $this->products[$product] = $quantity;     }          public function getQuantity($product)     {         return isset($this->products[$product]) ? $this->products[$product] :                FALSE;     }          public function getTotal($tax)     {         $total = 0.00;                  $callback =             function ($quantity, $product) use ($tax, &$total)             {                 $pricePerItem = constant(__CLASS__ . "::PRICE_" .                     strtoupper($product));                 //这里很妙，特殊的方式去获取了每个Item的Const值  const PRICE_EGGS    = 6.95;                 $total += ($pricePerItem * $quantity) * ($tax + 1.0);             };                  array_walk($this->products, $callback);         return round($total, 2);;     } } $my_cart = new Cart; // Add some items to the cart $my_cart->add('butter', 1); $my_cart->add('milk', 3); $my_cart->add('eggs', 6); // Print the total with a 5% sales tax. print $my_cart->getTotal(0.05) . "\n"; // The result is 54.29 ?>