探讨方法的重写(覆载)详解

<?php
 class Cart{
  public function Cart(){
   echo "正在调用Cart()<br />";
  }
  public function doSomething(){
   echo "正在调用doSomethimg()<br />";
  }
 }
 class Named_Cart extends Cart{
  function Named_Cart(){
   echo "正在调用Named_Cart()<br />";
  }
  function doSomething(){
   echo "正在调用Named_Cart::doSomething()<br />";
  }
 }
$myCart=new Cart();
$myCart->doSomething();
$myNamed_Cart=new Named_Cart();
$myNamed_Cart->doSomething();
?>