ICSR98 POSTER: Towards Programming Tool Support for Reuse

Robert Biddle and Ewan Tempero
Victoria University of Wellington, New Zealand
{robert,ewan}@mcs.vuw.ac.nz
Many approaches are being pursued to improve the effectiveness of software developers. Two important strategies are the development of tools to aid the programmer, and reuse of code to reduce the programmer's work. Both these strategies have led to improvements in productivity, but not to the degree hoped for. Of course, there are many factors involved, and the impact of non-technical issues can be significant. Even so, we believe a key reason success has been limited is that although reuse is the critical strategy to pursue, programming both with reuse and for reuse are difficult technical tasks. Accordingly, we propose the development of programming tools designed to explicitly support reuse. There are tools such as code repository systems that already directly support reuse, but we believe every kind of programming tool has a role to play in facilitating reuse. We are investigating what kind of support is necessary, how tools could provide such support, and are developing prototype tools to explore these ideas. In this poster we will explain our approach, relate our experience with two prototype tools, and outline our plans for future work.

Our approach is based on our earlier work, which involved developing a model for programming language support for reuse, and our work in computer science education, where the model has already been very useful. We propose to develop programming environment featuring tools that directly support those aspects that our model tells us are important to improving reusability. Our model is based on the concept of code assemblies, a symmetry of context reuse and component reuse , and dependencies that are beneficial or detrimental to reuse. The model was designed from consideration of programming language features and how they are used in programming, and so should also apply to a programming environment where the language features are actually used.

Our first prototype tools concentrate on assisting the programmer to understand the structure of their program from the viewpoint of reusability. Our education work suggests that students need such assistance during program development to keep a focus on how their program design relates to principles of reusability. We suspect that similar issues affect programmers in industry, although on a larger scale. One of our tools addresses static program structure, and so is similar to a CASE tool featuring a class browser. However, we have adapted the diagrammatic notation to highlight the interplay of context and component reuse. Another tool addresses dynamic program structure, and so is similar to a program visualisation system. Again, we use diagrams to illustrate the connections as code assemblies use, and are used by, other assemblies. In this tool the diagrams are animated as the program runs, and the programmer can inspect the changing structure to better understand the patterns that result, and so gain insight into how assemblies are, or might be, used and reused.

Our experience with these first prototypes has been positive, and we are encouraged that such tools really can facilitate programming for reusability. Moreover, our model does seem to match the needs of a programming environment. We are now developing a structure for tool support throughout the programming process. Broadly, we distinguish program construction and program exploration. In construction, there is support needed both in harnessing assemblies from outside (e.g. repositories), and from within (e.g. editors). In exploration, there is support needed both for the static program and the dynamic execution, and this support can extend to testing, profiling, and algorithm animation. We are now developing a second set of prototypes to test the overall structure, and to refine our understanding. We hope to address each kind of programming tool, and eventually develop an entire programming environment that explicitly supports reuse. This work is still in progress, and we hope this poster will encourage early feedback on our approach.