Programming by Demonstration , a user - oriented programming paradigm for graphic systems

Computer graphics development does not only need efficient approaches and programming paradigms for software designers. It also requires end-users to be able to program their own system. The goal of this paper is to show that the Programming by Demonstration (PbD) approach, where system end-users specify programs by designing examples of their behaviour, is now mature enough to constitute an attractive paradigm for graphic programming environments. Programming by Demonstration involves two aspects. First, it requires the capability for the system to associate each value, in the example, with one object (constant, internal variable or parameter) in the program. This constitutes the dynamic context management of the program. Second, it must assume the definition of dialogue conventions (dialogue protocols), which enable users to (implicitly) specify programs, with as few as possible changes to the user skills and to the interactive command language. We show in this paper how structuring the dynamic context provides for structured program context management, and how some "natural" dialogue conventions may be defined in order to enable the graphical specification of every control structure, including the general purpose recurrence-based loop structure, which is not supported, as far as we know, by any other PbD system. The system we have developed proves that the PbD approach is now a mature enough technology, enabling graphic systems end-users to really program their system.