php - 如何做一个PHP钩子(Hook)系统？

Question

如何在 PHP 应用程序中实现 Hook 系统以在代码执行之前或之后更改代码。 hookloader 类的基本架构如何适用于 PHP CMS(甚至是简单的应用程序)。那么如何将其扩展为完整的插件/模块加载器？

(另外，有没有关于CMS Hook 系统的书籍或教程？)

Answer 1

您可以将事件系统构建为 simple或您想要的复杂度。

/**
 * 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;
    }
}

添加事件

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');

然后这样调用

$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);