code: public static function getInstance($strTable)
  	{
  		if (!isset(static::$arrInstances[$strTable]))
  		{
  			static::$arrInstances[$strTable] = new static($strTable);
  		}
  
  		return static::$arrInstances[$strTable];
  	}
docs: Get one object instance per table
  
  @param string $strTable The table name
  
  @return DcaExtractor The object instance