Categories and Completeness of Visual Programming and Direct Manipulation

Recent innovations in visual programming and the use of direct manipulation for programming have demonstrated promise, but also raise questions about how far these approaches can be generalized. To clarify these issues, we present a categorization of systems for visual programming, programming-by-example, and similar systems. By examining each category, we elucidate the advantages, limitations, and ways to extend systems in each category. Our work makes it easier for researchers and designers to understand how visual programming languages (VPLs) and similar systems relate to each other, and how to extend them. We also indicate directions for future research.