A method or apparatus for use in generating an information system, wherein an object-oriented model ofthe information system is provided, themodel defining classes of information objects require to be supported by the information system in terms of their attributes, operations that maybe performed on the object, and an intended relationship (if any) between two or more of theobjects. Built-in or predefined descriptions of the operations which maybe performed on the objects are provided in terms of conditions that should hold initially, data that might be affected, and the desired results. An operation referenced in a class definition is then automatically expanded by adding a respective built-in or predefined description thereto within the object-oriented model of the information system. It is determined if the attributes of any other class defined within the model would be affected by the operation and, if so, the operation is automatically further expanded to include an update function to update one or more attributes determined to be affected by the operation accordingly.