class Event {     protected static $listens       = array();           public static function listen($event, $callback, $once=false){         if(!is_callable($callback)) return false;         self::$listens[$event][]    = array('callback'=>$callback, 'once'=>$once);         return true;     }           public static function one($event, $callback){         return self::listen($event, $callback, true);     }           public static function remove($event, $index=null){         if(is_null($index))             unset(self::$listens[$event]);         else             unset(self::$listens[$event][$index]);     }           public static function trigger(){         if(!func_num_args()) return;         $args                       = func_get_args();         $event                      = array_shift($args);         if(!isset(self::$listens[$event])) return false;         foreach((array) self::$listens[$event] as $index=>$listen){             $callback               = $listen['callback'];             $listen['once'] && self::remove($event, $index);             call_user_func_array($callback, $args);         }     } }

// 增加监听walk事件 Event::listen('walk', function(){     echo "I am walking...n"; }); // 增加监听walk一次性事件 Event::listen('walk', function(){     echo "I am listening...n"; }, true); // 触发walk事件 Event::trigger('walk'); /* I am walking... I am listening... */ Event::trigger('walk'); /* I am walking... */   Event::one('say', function($name=''){     echo "I am {$name}n"; });   Event::trigger('say', 'deeka'); // 输出 I am deeka Event::trigger('say', 'deeka'); // not run   class Foo {     public function bar(){         echo "Foo::bar() is calledn";     }           public function test(){         echo "Foo::foo() is called, agrs:".json_encode(func_get_args())."n";     } }   $foo    = new Foo;   Event::listen('bar', array($foo, 'bar')); Event::trigger('bar');   Event::listen('test', array($foo, 'test')); Event::trigger('test', 1, 2, 3);   class Bar {     public static function foo(){         echo "Bar::foo() is calledn";     } }   Event::listen('bar1', array('Bar', 'foo')); Event::trigger('bar1');   Event::listen('bar2', 'Bar::foo'); Event::trigger('bar2');   function bar(){     echo "bar() is calledn"; }   Event::listen('bar3', 'bar'); Event::trigger('bar3');