1 <?php 2  3 trait MetaTrait 4 { 5     private $methods = []; 6  7     public function addMethod($methodName,$methodCallable) 8     { 9         if (!is_callable($methodCallable))10             throw new InvalidArgumentException(‘Second param must be callable‘);11 12         //改变作用域到 get_called_class 的对象13         $this->methods[$methodName] = Closure::bind($methodCallable, $this, get_called_class());14 15     }16 17     public function __call($methodName, array $args)18     {19         if (isset($this->methods[$methodName])){20             return call_user_func_array($this->methods[$methodName],$args);21         }22 23         throw new RuntimeException(‘There is no method with the given name to call‘);24 25     }26 27 }28 29 class HackThursday30 {31     use MetaTrait;32 33     private $dayOfWeek = ‘Thursday‘;34 }35 36 37 $test = new HackThursday();38 $test->addMethod(‘when‘,function(){39     return $this->dayOfWeek;40 });41 42 echo $test->when(); //Thursday