Object class definition by generalization using upward inheritance

摘要

The authors show how the process of object class definition byngeneralization can be incorporated into object-oriented systems.nTraditional message handling, which is mainly based on downward propertyninheritance, is revised and extended to upward property inheritance, sonthat a maximum of reusability of code and data can be achieved.nDifferent types of semantic relationships that may hold between angeneralization class's subclasses and their attributes are identified.nThe different semantic relationships can then be utilized to producendifferent default treatments of messages and upward property propagation