Maintenance support for object-oriented programs

This paper describes some of the difficulties that may be expected in the maintenance of software developed using the new object oriented languages. The concepts of inheritance and of polymorphism provide the great strengths of these languages, but they also introduce difficulties in program analysis and understanding. The paper analyzes problems of dynamic binding, object dependencies, dispersed program structure, control of polymorphism, high-level understanding, and detailed code understanding. Examples are presented based on code from a PC Smalltalk environment and from studies of two systems under development at Bell Communications Research