public function write( $driver = null ) 
	{	
		if ( empty( $this->_instance_name ) ) 
		{
			throw new CCException("CCConfig::write - configuration name is missing.");
		}
		
		// set the dirver
		if ( !is_null( $driver ) )
		{
			$this->driver( $driver );
		}
		
		// run write
		$this->_driver->write( $this->_instance_name, $this->_data );
	}