Growl notifications in php

growl.php

<?php

class Growl {

	private $_command;
	private $_valid_args = array('title', 'name', 'appicon', 'message', 'icon', 'iconpath', 'image', 'priority', 'identifier', 'wait', 'host', 'password', 'upd', 'port', 'auth', 'progress');

	public function __construct($options = array())
	{
		if( ! empty($options))
		{
			$this->initialize($options);
		}
	}

	public function initialize($options)
	{
		$this->_command = 'growlnotify';
		foreach($options as $k=>$v)
		{
			if(in_array($k, $this->_valid_args))
			{
				$this->_command .= " --$k \"$v\"";
			}
		}
	}

	public function notify()
	{
		if($this->exists())
		{
			$cmd = $this->_command;
			`$cmd`;
		}
	}

	public function version()
	{
		return substr(`growlnotify -v`, 12, 5);
	}

	public function exists()
	{
		return (`which growlnotify` != '');
	}
}

$growl = new Growl(array('message'=>'HELLO WORLD'));
$growl->notify();