Abstract-Static type systems play an essential role in contemporary programming languages. Despite their importance, whether static type systems influence human software development capabilities remains an open question. One frequently mentioned argument for static type systems is that they improve the maintainability of software systems-an often used claim for which there is no empirical evidence. This paper describes an experiment which tests whether static type systems improve the maintainability of software systems. The results show rigorous empirical evidence that static type are indeed beneficial to these activities, except for fixing semantic errors.

Abstract-Programming experience is an important confounding parameter in controlled experiments regarding program comprehension. In literature, ways to measure or control programming experience vary. Often, researchers neglect it or do not specify how they controlled it. We set out to find a well-defined understanding of programming experience and a way to measure it. From published comprehension experiments, we extracted questions that assess programming experience. In a controlled experiment, we compare the answers of 128 students to these questions with their performance in solving program-comprehension tasks. We found that self estimation seems to be a reliable way to measure programming experience. Furthermore, we applied exploratory factor analysis to extract a model of programming experience. With our analysis, we initiate a path toward measuring programming experience with a valid and reliable tool, so that we can control its influence on program comprehension.

AspectJ is a well-established programming language for the implementation of aspect-oriented programs. It supports the aspectoriented programming paradigm by providing a special unit, called "aspect", which encapsulates crosscutting code. While with AspectJ a suitable aspect-oriented programming language is at hand, no feasible modeling language is available that supports the design of AspectJ programs. In this work, such a design notation for AspectJ programs is presented based on the UML. It provides representations for all language constructs in AspectJ and specifies an UML implementation of AspectJ's weaving mechanism. The design notation eases the perception of aspect-orientation and AspectJ programs. It carries over the advantages of aspectorientation to the design level.

Programming experience is an important confounding parameter in controlled experiments regarding program comprehension. In literature, ways to measure or control programming experience vary. Often, researchers neglect it or do not specify how they controlled for it. We set out to find a well-defined understanding of programming experience and a way to measure it. From published comprehension experiments, we extracted questions that assess programming experience. In a controlled experiment, we compare the answers of computer-science students to these questions with their performance in solving program-comprehension tasks. We found that self estimation seems to be a reliable way to measure programming experience. Furthermore, we applied exploratory and confirmatory factor analyses to extract and evaluate a model of programming experience. With our analysis, we initiate a path toward validly and reliably measuring and describing programming experience to better understand and control its influence in program-comprehension experiments.

When specifying pointcuts, i.e. join point selections, in AspectOriented Software Development, developers have in different situations different conceptual models in mind. Aspect-oriented programming languages are usually capable to support only a small subset of them, but not all. In order to communicate aspectoriented design among developers, though, it is inevitable that the underlying conceptual model used in its join point selections remains unchanged. As a solution to this dilemma, we detail three different conceptual models in this paper that are frequently used in aspect-oriented applications. These models are illustrated using sample implementations from existing literature. Then, we introduce corresponding modeling notations based on Join Point Designation Diagrams (JPDDs) which are capable to express join point selections complying to those models. Finally, we discuss the suitability of these notations to express a desired join point selection.