INHERITANCE

• INHERITANCE: A SUBCLASS CAN BE DEFINED ON THE BASIS OF A SUPERCLASS DEFINITION
  
  
  • SUBCLASS INHERITS: ATTRIBUTES, METHODS & MESSAGES OF SUPERCLASS
  • IN ADDITION SUBCLASS CAN HAVE NON INHERITED ATTRIBUTES, METHODS & MESSAGES
  
  
• IN SOME SYSTEMS A CLASS CAN HAVE SEVERAL SUPERCLASSES: MULTIPLE INHERITANCE

• IF AN ATTRIBUTE OR METHOD IS DEFINED EXPLICITLY IN THE SUBCLASS IT OVERRIDES A SAME-NAMED COUNTER PART IN THE SUPERCLASS
  
  
  • I.E. IT IS NOT INHERITED
  
  
• CLASSES CAN BE ORGANIZED AROUND INHERITANCE HIERARCHIES (TREES IN THE CASE OF SINGLE INHERITANCE SYSTEMS)
  
  
  • ORTHOGONAL TO AGGREGATION HIERARCHIES
  • CANNOT HAVE CYCLES
  
  

Previous: Page 16a Next: Page 17a Up A Level: TOC

Ugo O. Gagliardi
GSD-6306 Spring 2003-2004