<?php

//...

	public function begin()
	{
		$this->tx = array();
	}
	
	public function commit()
	{
	}
	
	public function rollback()
	{
		foreach($this->tx as $k => $v) $this->data[$k] = $v;
	}
	
	public function __set($k, $v)
	{
		if(!isset($this->data[$k])) $this->data[$k] = null;
		if(!isset($this->tx[$k])) $this->tx[$k] = $this->data[$k];
		$this->data[$k] = $v;
	}

//...

?>