Writing a ConnectListener

As the name suggests, a ConnectListener will be notified every time Swift connects to the SMTP server or other MTA. A plugin which implements the Swift_Events_ConnectListener interface will be passed an instance of Swift_Events_ConnectEvent when a connection is established.

The interface for a plugin which will be a ConnectListener is shown below:

/**
 * Contains the list of methods a plugin requiring the use of a ConnectEvent must implement
 * @package Swift_Events
 * @author Chris Corbyn <chris@w3style.co.uk>
 */
interface Swift_Events_ConnectListener extends Swift_Events_Listener
{
	/**
	 * Executes when Swift initiates a connection
	 * @param Swift_Events_ConnectEvent Information about the connection
	 */
	public function connectPerformed(Swift_Events_ConnectEvent $e);
}

If you’re using PHP5, you must declare that your plugin implements this interface. For PHP4, all you need to do is make sure the method connectPerformed($e) exists in you plugin. You cannot using type-checking in PHP4.

In PHP5, your plugin would be declared like this:

class MyPlugin implements Swift_Events_ConnectListener
{
    public function connectPerformed(Swift_Events_ConnectEvent $e) {}
}

In PHP4, that simply becomes:

class MyPlugin extends Swift_Events_Listener
{
    function connectPerformed(&$e) {}
}

Let’s take the example that you want to add a custom line to the log whenever Swift connects. All event objects have a common method of getSwift() which returns a reference to the instance of Swift which generated the event. Working with Swift here is just like working with it anywhere else, so adding a line to the log at connect is a pretty basic example.

class ConnectLoggerPlugin implements Swift_Events_ConnectListener
{
    public function connectPerformed(swift_Events_ConnectEvent $e)
    {
        $swift = $e->getSwift();
        if (!($enabled = $swift->log->isEnabled()))
            $swift->log->enable();
        $swift->log->add("Swift connected and this plugin saw it happen!");
        if (!$enabled) $swift->log->disable();
    }
}

You need to remember that in PHP4, you will absolutely need to use the reference operator or you’ll be working with a copy of Swift and it won’t work.

You can also get a copy of the connection object that established the connection by calling:

$connection = $e->getConnection();

It’s unlikely you’d ever want to tamper with the connection, but the ability exists if you really do.