如何做一个PHP钩子系统？

Question

如何在PHP应用程序中实现钩子系统在执行之前或之后更改代码.如何将钩子类的基本体系结构用于PHP CMS(甚至是简单的应用程序).那怎么可以扩展到一个完整的插件/模块加载器？

(另外,CMS挂钩系统上有任何书籍或教程吗？)

Answer 1

您可以根据需要构建简单或复杂的事件系统.

/**
 * Attach (or remove) multiple callbacks to an event and trigger those callbacks when that event is called.
 *
 * @param string $event name
 * @param mixed $value the optional value to pass to each callback
 * @param mixed $callback the method or function to call - FALSE to remove all callbacks for event
 */
function event($event, $value = NULL, $callback = NULL)
{
    static $events;

    // Adding or removing a callback?
    if($callback !== NULL)
    {
        if($callback)
        {
            $events[$event][] = $callback;
        }
        else
        {
            unset($events[$event]);
        }
    }
    elseif(isset($events[$event])) // Fire a callback
    {
        foreach($events[$event] as $function)
        {
            $value = call_user_func($function, $value);
        }
        return $value;
    }
}

添加活动

event('filter_text', NULL, function($text) { return htmlspecialchars($text); });
// add more as needed
event('filter_text', NULL, function($text) { return nl2br($text); });
// OR like this
//event('filter_text', NULL, 'nl2br');

然后这样称呼它

$text = event('filter_text', $_POST['text']);

或者像这样删除该事件的所有回调

event('filter_text', null, false);