php中Closure::bind用法(手册记录)

　　手册中　Closure::bind — 复制一个闭包，绑定指定的$this对象和类作用域。

　　具体参数可以看手册，这里记录下这个方法的实际用处．

 <?php

 trait MetaTrait
 {
     private $methods = [];

     public function addMethod($methodName,$methodCallable)
     {
         if (!is_callable($methodCallable))
             throw new InvalidArgumentException('Second param must be callable');

         //改变作用域到 get_called_class 的对象
         $this->methods[$methodName] = Closure::bind($methodCallable, $this, get_called_class());

     }

     public function __call($methodName, array $args)
     {
         if (isset($this->methods[$methodName])){
             return call_user_func_array($this->methods[$methodName],$args);
         }

         throw new RuntimeException('There is no method with the given name to call');

     }

 }

 class HackThursday
 {
     use MetaTrait;

     private $dayOfWeek = 'Thursday';
 }

 $test = new HackThursday();
 $test->addMethod('when',function(){
     return $this->dayOfWeek;
 });

 echo $test->when(); //Thursday

　　其实这个方法就是以前说过的 Closure::bindTo() 的静态版本, 和PHP 使用reflection时的问题,以及解决方案这篇一起看加深理解．