Lightweight Analysis of Object Interactions

The state of the practice in object-oriented software development has moved beyond reuse of code to reuse of conceptual structures such as design patterns. This paper draws attention to some difficulties that need to be solved if this style of development is to be supported by formal methods. In particular, the centrality of object interactions in many designs makes traditional reasoning less useful, since classes cannot be treated fruitfully in isolation from one another. We propose some ideas towards dealing with these issues: a relational model of heap structure capable of expressing sharing and mutual influence between objects; a declarative specification style that works in the presence of collaboration; and a tool-supported constraint analysis to expose problems in a diagram that captures, at a design level, a pattern of interaction. We illustrate these ideas with an example taken from a program used in the formatting of this paper.