PHP的回调方法
回调，不用解释了，我们就来看下PHP怎么实现回调

1.首先建一个对象
class Product{
  public $name; //为了方便测试
 
   function __construct($name){
    $this->name=$name;
   }
}

2.使用回调
class ProcessSale{
  private $callbacks;

  //设置回调方法
  function registerCallBack($callback){
    if(!is_callable($callback)){
      throw new Exception("xxxxxx");
    }

    $this->callbacks[]=$callback;
  }

  function sale($product){
   print "{$product->name}:processing \n";

   foreach($this->callbacks as $callback){
     call_user_func($callback,$product);
   }
  }
}

3.测试
$logger = function($product){
  print "logging ({$product->name})";
}

$processor = new ProcessSale();
$processor->registerCallBack($logger);

$processor->sale(new Product("测试"));