Thomas Leich

FeatureIDE: An extensible framework for feature-oriented software development

FeatureIDE is an open-source framework for feature-oriented software development (FOSD) based on Eclipse. FOSD is a paradigm for the construction, customization, and synthesis of software systems. Code artifacts are mapped to features, and a customized software system can be generated given a selection of features. The set of software systems that can be generated is called a software product line (SPL). FeatureIDE supports several FOSD implementation techniques such as feature-oriented programming, aspect-oriented programming, delta-oriented programming, and preprocessors. All phases of FOSD are supported in FeatureIDE, namely domain analysis, requirements analysis, domain implementation, and software generation.

FeatureC++: on the symbiosis of feature-oriented and aspect-oriented programming

This paper presents FeatureC++, a novel language extension to C++ that supports Feature-Oriented Programming (FOP) and Aspect-Oriented Programming (AOP). Besides well-known concepts of FOP languages, FeatureC++ contributes several novel FOP language features, in particular multiple inheritance and templates for generic programming. Furthermore, FeatureC++ solves several problems regarding incremental software development by adopting AOP concepts. Starting our considerations on solving these problems, we give a summary of drawbacks and weaknesses of current FOP languages in expressing incremental refinements. Specifically, we outline five key problems and present three approaches to solve them: Multi Mixins, Aspectual Mixin Layers, and Aspectual Mixins that adopt AOP concepts in different ways. We use FeatureC++ as a representative FOP language to explain these three approaches. Finally, we present a case study to clarify the benefits of FeatureC++ and its AOP extensions.

Aspectual Feature Modules

Two programming paradigms are gaining attention in the overlapping fields of software product lines (SPLs) and incremental software development (ISD). Feature-oriented programming (FOP) aims at large-scale compositional programming and feature modularity in SPLs using ISD. Aspect-oriented programming (AOP) focuses on the modularization of crosscutting concerns in complex software. Although feature modules, the main abstraction mechanisms of FOP, perform well in implementing large-scale software building blocks, they are incapable of modularizing certain kinds of crosscutting concerns. This weakness is exactly the strength of aspects, the main abstraction mechanisms of AOP. We contribute a systematic evaluation and comparison of FOP and AOP. It reveals that aspects and feature modules are complementary techniques. Consequently, we propose the symbiosis of FOP and AOP and aspectual feature modules (AFMs), a programming technique that integrates feature modules and aspects. We provide a set of tools that support implementing AFMs on top of Java and C++. We apply AFMs to a nontrivial case study demonstrating their practical applicability and to justify our design choices.

FeatureIDE: A tool framework for feature-oriented software development

Tools support is crucial for the acceptance of a new programming language. However, providing such tool support is a huge investment that can usually not be provided for a research language. With FeatureIDE, we have built an IDE for AHEAD that integrates all phases of feature-oriented software development. To reuse this investment for other tools and languages, we refactored FeatureIDE into an open source framework that encapsulates the common ideas of feature-oriented software development and that can be reused and extended beyond AHEAD. Among others, we implemented extensions for FeatureC++ and FeatureHouse, but in general, FeatureIDE is open for everybody to showcase new research results and make them usable to a wide audience of students, researchers, and practitioners.

Aspectual mixin layers: aspects and features in concert

Feature-Oriented Programming (FOP) decomposes complex software into features. Features are main abstractions in design and implementation. They reflect user requirements and incrementally refine one another. Although, features crosscut object-oriented architectures they fail to express all kinds of crosscutting concerns. This weakness is exactly the strength of aspects, the main abstraction mechanism of Aspect-Oriented Programming (AOP). In this article we contribute a systematic evaluation and comparison of both paradigms, AOP and FOP, with focus on incremental software development. It reveals that aspects and features are not competing concepts. In fact AOP has several strengths to improve FOP in order to implement crosscutting featuresSymmetrically, the development model of FOP can aid AOP in implementing incremental designs. Consequently, we propose the architectural integration of aspects and features in order to profit from both paradigms. We introduce aspectual mixin layers (AMLs), an implementation approach that realizes this symbiosis. A subsequent evaluation and a case study reveal that AMLs improve the crosscutting modularity of features as well as aspects become well integrated into incremental development style.

Understanding understanding source code with functional magnetic resonance imaging

Program comprehension is an important cognitive process that inherently eludes direct measurement. Thus, researchers are struggling with providing suitable programming languages, tools, or coding conventions to support developers in their everyday work. In this paper, we explore whether functional magnetic resonance imaging (fMRI), which is well established in cognitive neuroscience, is feasible to soundly measure program comprehension. In a controlled experiment, we observed 17 participants inside an fMRI scanner while they were comprehending short source-code snippets, which we contrasted with locating syntax errors. We found a clear, distinct activation pattern of five brain regions, which are related to working memory, attention, and language processing---all processes that fit well to our understanding of program comprehension. Our results encourage us and, hopefully, other researchers to use fMRI in future studies to measure program comprehension and, in the long run, answer questions, such as: Can we predict whether someone will be an excellent programmer? How effective are new languages and tools for program understanding? How should we train programmers?

Tool support for feature-oriented software development: featureIDE: an Eclipse-based approach

Software program families have a long tradition and will gain momentum in the future. Todays research tries to move software development to a new quality of industrial production. Several solutions concerning different phases of the software development process have been proposed in order to cope with different problems of program family development. A major problem of program family engineering is still the missing tool support. The vision is an IDE that brings all phases of the development process together consistently and in a user-friendly manner. This paper focuses on AHEAD, a prominent design methodology and architectural model for feature-based program families. We present our first results on developing an Eclipse-based IDE that supports building program families following the AHEAD architecture model. Starting from current weaknesses and pitfalls in implementing program families we outline several challenges of the feature-based development process. Thereupon, we present our ideas to face these challenges and a resulting integrated tool chain based on Eclipse.

Do background colors improve program comprehension in the #ifdef hell?

Software-product-line engineering aims at the development of variable and reusable software systems. In practice, software product lines are often implemented with preprocessors. Preprocessor directives are easy to use, and many mature tools are available for practitioners. However, preprocessor directives have been heavily criticized in academia and even referred to as “#ifdef hell”, because they introduce threats to program comprehension and correctness. There are many voices that suggest to use other implementation techniques instead, but these voices ignore the fact that a transition from preprocessors to other languages and tools is tedious, erroneous, and expensive in practice. Instead, we and others propose to increase the readability of preprocessor directives by using background colors to highlight source code annotated with ifdef directives. In three controlled experiments with over 70 subjects in total, we evaluate whether and how background colors improve program comprehension in preprocessor-based implementations. Our results demonstrate that background colors have the potential to improve program comprehension, independently of size and programming language of the underlying product. Additionally, we found that subjects generally favor background colors. We integrate these and other findings in a tool called FeatureCommander, which facilitates program comprehension in practice and which can serve as a basis for further research.

FeatureIDE: taming the preprocessor wilderness

Preprocessors are a common way to implement variability in software. They are used in numerous software systems, such as operating systems and databases. Due to the ability of preprocessors to enable and disable code fragments, not all parts of the program are active at the same time. Thus, programmers and tools need to handle the interactions resulting from annotations in the program. With our Eclipse-based tool FeatureIDE, we provide tool support to tackle multiple challenges with preprocessors, such as code comprehension, feature traceability, separation of concerns, and program analysis. With FeatureIDE, instead of focusing on one particular preprocessor, we provide tool support, which can easily be adopted for further preprocessors. Currently, we support development with CPP, Antenna, and Munge. https://youtu.be/jVe7f32mLCQ

Access control in feature-oriented programming

In feature-oriented programming (FOP) a programmer decomposes a program in terms of features. Ideally, features are implemented modularly so that they can be developed in isolation. Access control mechanisms in the form of access or visibility modifiers are an important ingredient to attain feature modularity as they allow programmers to hide and expose internal details of a modules implementation. But developers of contemporary feature-oriented languages have not considered access control mechanisms so far. The absence of a well-defined access control model for FOP breaks encapsulation of feature code and leads to unexpected program behaviors and inadvertent type errors. We raise awareness of this problem, propose three feature-oriented access modifiers, and present a corresponding access modifier model. We offer an implementation of the model on the basis of a fully-fledged feature-oriented compiler. Finally, by analyzing ten feature-oriented programs, we explore the potential of feature-oriented modifiers in FOP.