<?phpclass LaceActivity extends LaceData{	var $expiry = '';	function __construct()	{		$this->LaceActivity();	}	function LaceActivity()	{		$this->setExpiry(time() - (LACE_TIMEOUT * 60));		$this->setFile(LACE_ACTIVITY_FILE);		$this->getData();		register_shutdown_function(array(&$this, 'storeData'));	}	function setExpiry($expiry)	{		$this->expiry = $expiry;	}	function prepareDataForRetrieval($data)	{		if (is_array($data))		{			foreach ($data as $row)			{				list($name, $last_post) = array_map('trim', explode('|', $row));				$this->add($name, $last_post);			}			$this->purgeExpired();		}		else		{			$this->data = array();		}	}	function prepareDataForStorage()	{		$data = '';		if (is_array($this->data))		{			foreach($this->data as $name => $last_post)			{				$data .= $name.'|'.$last_post."\n";			}		}		return $data;	}	function purgeExpired()	{		if (is_array($this->data))		{			foreach ($this->data as $name => $last_post)			{				if ($last_post < $this->expiry)				{					$this->deleteByKey($name);				}			}		}	}	function changeName($from, $to)	{		if (is_array($this->data) && array_key_exists($from, $this->data))		{			$this->deleteByKey($from);		}		$this->add($to, time());	}	function update($name)	{		return parent::update($name, time());	}	function getUsers()	{		$users = (count($this->data) > 0) ? array_keys($this->data) : array();		natcasesort($users);		return $users;	}	function computeHash()	{		$hashVal = is_array($this->data) ? array_keys($this->data) : uniqid(rand(0,10));		return md5(serialize($hashVal));	}}