Co-Evolution of Object-Oriented Software Design and Implementation

Abstract

Modern-day software development shows a number of feedback loops between various phases in its life cycle; object-oriented software is particularly prone to this. Whereas descending through the different levels of abstraction is relatively straightforward and well supported by methods and tools, the synthesis of design information from an evolving implementation is far from obvious. This is why in many instances, analysis and design is used to initiate software development while evolution is directly applied to the implementation. Keeping design information synchronized is often reduced to a token activity, the first to be sacrificed in the face of time constraints. In this light, architectural styles are particularly difficult to enforce, since they can, by their very nature, be seen to crosscut an implementation. This contribution reports on a number of experiments to use logic meta-programming (LMP) to augment an implementation with enforceable design concerns, including architectural concerns. LMP is an instance of hybrid language symbiosis, merging a declarative (logic) meta-level language with a standard object-oriented base language. This approach can be used to codify design information as constraints or even as a process for code generation. LMP is an emerging technique, not yet quite out of the lab. However, it has already been shown to be very expressive: it incorporates mechanisms such as pre/post conditions and aspect-oriented programming. We found the promise held by LMP extremely attractive, hence this chapter.