Program Development on Graphical Workstations

The aim of this paper is to emphasize the merits of program development on graphical workstations. A workstation with a graphical display and a pointing device is an interesting base for new programming environments. Sufficient machine resources are provided to support advanced software development tools, and a considerable improvement of the programmer-machine interaction is possible. Program editing on graphical workstations is discussed. Using windows, a program can simultaneously be presented at several abstraction levels and hereby good program survey and rapid program navigation is provided. We discuss how to cope with the large set of commands in syntax-directed editors, and how to create programs using the pointing device as the primary input medium. Testing incomplete program sketches by simulating unimplemented facilities via so-called state editing is explained. Simple graphical means seem to be useful when observing the program state. It is argued why continuous program observation combined with programmer controlled execution speed (including reverse execution) is valuable. Examples are drawn from the Ekko design - a proposed integrated program development system for graphical workstations - and from an implemented syntax-directed editor on a Perq workstation