12th European Conference on Object-Oriented Programming Brussels, Belgium, July 20 - 24, 1998
	Tutorial T3

Using Subject-Oriented Programming to Overcome Common Problems in Object-Oriented Software Development and Evolution

Subject-oriented programming (SOP) is a practical approach to object-oriented programming-in-the-large. SOP addresses some well-known limitations of object-oriented development without forcing developers to adopt new languages or abandon the object-oriented paradigm. These limitations include weaknesses in:

• Non-invasive system extension and evolution: Subclassing and design patterns help but are insufficient.
• Large-scale reuse and integration: With its focus on small-scale objects, object-oriented development does not provide sufficient mechanisms to achieve large-scale reuse or integration of off-the-shelf system components without significant prior planning.
• System decomposition: By-object/class system decomposition is useful for modeling data-centric aspects of a system. Other decompositions (e.g., by-feature; by-function) are better for modeling other aspects, however. Without them, maintainability, comprehensibility, and reusability suffer.
• Multi-team and decentralized development: Object-oriented development leads to contention over shared, centralized classes. It forces all developers to agree on a single domain model, rather than using models more appropriate to their tasks.

This tutorial will present the SOP approach and show developers how to use both the paradigm and tool support for SOP.

Harold Ossher co-invented subject-oriented programming in 1993. He manages a group that has built C++ support and prototype Smalltalk and Java (in progress) support for subjects. Peri Tarr joined the group in 1996. She has a strong background in software engineering and the application of subjects to it.