Explicit Programming

Avi Bryant, Andrew Catton, Kris De Volder, and Gail C. Murphy.

To appear in the Proceedings of 1st International Conference on Aspect-Oriented Software Development, April 2002, p. 10-18.

Abstract

Many design concepts can be expressed only indirectly in source code. When this occurs, a single concept at design results in a verbose amount of code that is scattered across the system structure. In this paper, we present explicit programming, an approach that enables a developer to introduce new vocabulary into the source to capture a design concept explicitly. An introduced vocabulary item modularizes the implementation details associated with a design concept, reducing the scattering of code needed to express the concept. The vocabulary item appears in the code where the concept is needed; uses of the vocabulary may thus remain distributed through the code. We believe explicit programming provides a useful engineering point, balancing modularization and separation in (at least) two cases. First, when a design concept is tightly coupled with particular constructs in a program, separation is unlikely to lead to any benefits of reusability or comprehensibility. Second, concepts that emerge as a system evolves can be encapsulated and recorded, paving the way for later separation when conditions warrant it. We introduce ELIDE, a tool that supports explicit programming in Java, and describe several cases showing the utility of the explicit programming approach.