我们有一个名为 $saved 的公共数组，其中包含在方法之间共享所需的大量数据(下面的示例(...
class Common {
public $saved = array();
public function setUser($data) {
$this->saved['user_data'] = $data;
}
public function getUserID() {
return $this->saved['user_data']['id'];
}
}
实际上有数千行代码像这样工作。
问题在于，在某些方法中正在创建扩展Common类的新实例，因此当它们访问$saved时，它不会保存相同的数据。
解决方案是使$saved成为静态变量，但是我无法更改对$this->saved的所有引用，因此我想尝试保持代码相同，但使其充当静态。
这是我尝试使$this->saved调用静态...
class PropertyTest {
private $data = array();
public function __set($name, $value) {
$this->data[$name] = $value;
}
public function __get($name) {
if (array_key_exists($name, $this->data)) {
return $this->data[$name];
}
return null;
}
public function __isset($name) {
return isset($this->data[$name]);
}
public function __unset($name) {
unset($this->data[$name]);
}
}
class Common {
public $saved;
private static $_instance;
public function __construct() {
$this->saved = self::getInstance();
}
public static function getInstance() {
if (self::$_instance === null) {
self::$_instance = new PropertyTest();
self::$_instance->foo = array();
}
return self::$_instance->foo;
}
}
这在设置变量时不太有效，它似乎不会保持静态(下面的测试用例(......
class Template extends Common {
public function __construct() {
parent::__construct();
$this->saved['user_data'] = array('name' => 'bob');
$user = new User();
}
}
class User extends Common {
public function __construct() {
parent::__construct();
$this->saved['user_data']['name'] .= " rocks!";
$this->saved['user_data']['id'] = array(400, 10, 20);
}
}
$tpl = new Template();
print_r($tpl->saved['user_data']);
$this->saved初始化时User为空，并且似乎不是同一个变量，最后的print_r只显示 name => bob 的数组。
有什么想法吗？
首先，我不得不说，IMO，将实例的属性用作类的属性并不是那么好($saved没有声明为static但它的值与所有实例共享(。
这是 http://codepad.org/8hj1MOCT 的工作版本，这是注释的代码。基本上，诀窍在于同时使用 ArrayAccess 接口和单例模式。
class Accumulator implements ArrayAccess {
private $container = array();
private static $instance = null;
private function __construct() {
}
public function getInstance() {
if( self::$instance === null ) {
self::$instance = new self();
}
return self::$instance;
}
public function offsetSet($offset, $value) {
if (is_null($offset)) {
$this->container[] = $value;
} else {
$this->container[$offset] = $value;
}
}
public function offsetExists($offset) {
return isset($this->container[$offset]);
}
public function offsetUnset($offset) {
unset($this->container[$offset]);
}
public function offsetGet($offset) {
return isset($this->container[$offset]) ? $this->container[$offset] : null;
}
}
class Common {
public $saved = null;
public function __construct() {
// initialize the "saved" object's property with the singleton
// that variable can be used with the array syntax thanks to the ArrayAccess interface
// so you won't have to modify your actual code
// but also, since it's an object, this local "$this->saved" is a reference to the singleton object
// so any change made to "$this->saved" is in reality made into the Accumulator::$instance variable
$this->saved = Accumulator::getInstance();
}
public function setUser($data) {
$this->saved['user_data'] = $data;
}
public function getUser() {
return $this->saved['user_data'];
}
}
class Template extends Common {
// you can redeclare the variable or not. Since the property is inherited, IMO you should not redeclare it, but it works in both cases
// public $saved = null;
public function __construct() {
// maybe we can move this initialization in a method in the parent class and call that method here
$this->saved = Accumulator::getInstance();
}
}
我认为
这个实现有很多问题很可能会回来咬你。但是，在当前的实现中，您每次都会构建一个新实例(尽管通过静态调用(。
相反，请使用 getInstance(( 作为您的单例钩子，并将您的__construct设为私有，因为您只能从 Common 类的上下文中访问它。
这样：
class Common {
public $saved;
private static $_instance;
private function __construct() {
}
public static function getInstance() {
if (self::$_instance === null) {
self::$_instance = new self();
... any other modifications you want to make ....
}
return self::$_instance;
}
}
并且永远不要运行 parent：：_construct((，而是始终使用 getInstance(( 方法。
您可能还想放弃扩展此单例类的想法。这确实是一个糟糕的反模式，从长远来看可能会给您带来许多问题。相反，只需维护一个其他类可以读取/写入的Common类。由于它是单例，因此您无需担心注射。
我似乎已经解决了这个问题，通过$this->saved引用静态变量，它可以工作......
class Common {
private static $savedData = array();
public $saved;
public function __construct() {
$this->saved =& self::$savedData;
}
}