PHP SplObjectStorage使用实例

php spl splobjectstorage是用来存储一组对象的，特别是当你需要唯一标识对象的时候。
php spl splobjectstorage类实现了countable,iterator,serializable,arrayaccess四个接口。可实现统计、迭代、序列化、数组式访问等功能。

看下面一个简单的例子：

class a {
  public $i;
  public function __construct($i) {
    $this->i = $i;
  }
}
 
$a1 = new a(1);
$a2 = new a(2);
$a3 = new a(3);
$a4 = new a(4);
 
$container = new splobjectstorage();
 
//splobjectstorage::attach 添加对象到storage中
$container->attach($a1);
$container->attach($a2);
$container->attach($a3);
 
//splobjectstorage::detach 将对象从storage中移除
$container->detach($a2);
 
//splobjectstorage::contains用于检查对象是否存在storage中
var_dump($container->contains($a1)); //true
var_dump($container->contains($a4)); //false
 
//遍历
$container->rewind();
while($container->valid()) {
  var_dump($container->current());
  $container->next();
}