php实现事件监听与触发的方法

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,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','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');