CAN END-USERS PROGRAM?

In recent years, personal computing has changed direction and is now more inclined towards the world of mobile computing. This means that end-users expect a simpler and more personalized experience. To achieve the highest level of customization, end-users must develop their own applications. However, end-users usually lack in having the right skills for that task. To address this problem, many end-users programming languages and frameworks have been devised. These are particularly aimed at reducing syntax and cognitive gaps. However, some of the existing solutions reduced the expressiveness of the language and thus reduced the generality of the program, while others remains too complex for end-users. In this work we devise a new framework, named Dev4Me, designed from the ground up to provide end-users a solution for developing mobile and personal apps. The framework is made up of a new form-based language, an Integrated Development Environment (IDE) and an execution environment. The new framework enables the users to develop, test, debug and use their own apps in a few simple steps, using familiar form filling experience

Graphical definitions : expanding spreadsheet languages through direct manipulation and gestures

Until now, attempts to extend the one-way constraint evaluation model of the spreadsheet paradigm to support complex objects, such as colored circles or user-defined types, have led to approaches featuring either a direct way of creating objects graphically or strong compatibility with the spreadsheet paradigm, but not both. This inability to conveniently go beyond numbers and strings without straying outside the spreadsheet paradigm has been a limiting factor in the applicability of spreadsheets. In this thesis we present a technique that removes this limitation, allowing complex objects to be programmed directly--and in a manner that fits seamlessly within the spreadsheet paradigm--using direct manipulation and gestures. We also present the results of an empirical study which suggests that programmers can use this technique to program complex objects faster and with fewer errors. The graphical definitions technique not only expands the applicability of spreadsheet languages, it also adds to their support for exploratory programming and to their scalability

Automated model-based spreadsheet debugging

Spreadsheets are interactive data organization and calculation programs that are developed in spreadsheet environments like Microsoft Excel or LibreOffice Calc. They are probably the most successful example of end-user developed software and are utilized in almost all branches and at all levels of companies. Although spreadsheets often support important decision making processes, they are, like all software, prone to error. In several cases, faults in spreadsheets have caused severe losses of money. Spreadsheet developers are usually not educated in the practices of software development. As they are thus not familiar with quality control methods like systematic testing or debugging, they have to be supported by the spreadsheet environment itself to search for faults in their calculations in order to ensure the correctness and a better overall quality of the developed spreadsheets. This thesis by publication introduces several approaches to locate faults in spreadsheets. The presented approaches are based on the principles of Model-Based Diagnosis (MBD), which is a technique to find the possible reasons why a system does not behave as expected. Several new algorithmic enhancements of the general MBD approach are combined in this thesis to allow spreadsheet users to debug their spreadsheets and to efficiently find the reason of the observed unexpected output values. In order to assure a seamless integration into the environment that is well-known to the spreadsheet developers, the presented approaches are implemented as an extension for Microsoft Excel. The first part of the thesis outlines the different algorithmic approaches that are introduced in this thesis and summarizes the improvements that were achieved over the general MBD approach. In the second part, the appendix, a selection of the author's publications are presented. These publications comprise (a) a survey of the research in the area of spreadsheet quality assurance, (b) a work describing how to adapt the general MBD approach to spreadsheets, (c) two new algorithmic improvements of the general technique to speed up the calculation of the possible reasons of an observed fault, (d) a new concept and algorithm to efficiently determine questions that a user can be asked during debugging in order to reduce the number of possible reasons for the observed unexpected output values, and (e) a new method to find faults in a set of spreadsheets and a new corpus of real-world spreadsheets containing faults that can be used to evaluate the proposed debugging approaches