On the Design of Software Composition Mechanisms and the Analysis of Composition Conflicts

A large variety of programming languages exists, and these languages differ substantially with regard to the modularization and composition mechanisms they support. Such differences may have an impact on important software engineering characteristics, such as reusability, exibility, analyzability and stability. The design of software languages often entails making trade-offs between such characteristics. In this thesis, we study several state-of-the-art programming languages, in particular focusing on aspect-oriented languages. Aspects have been proposed as a means to improve software modularization in the presence of crosscutting concerns; the aim is that such improved modularization leads to better software maintainability. In this thesis, we strive to improve several engineering characteristics, in particular those that are influenced by the use of aspect-oriented languages. Specically, to improve the analyzability of programs written in aspect-oriented languages, we propose several analysis techniques. First, we introduce an algorithm that ensures the declarative application of introductions by aspects. However, the use of introductions can also cause new kinds of composition conflicts. We propose automated tools to detect such conflicts. In addition, we employ graph-based formalisms to detect several other categories of issues related to introductions by aspects. In addition, we attempt to improve changeability, both from the perspective of software engineers who write programs using aspects, as well as from the perspective of language engineers who prototype new (aspect) languages. To this end, we define an aspect metamodel interpreter framework, which can be used to define many aspect-oriented languages, including domain-specific aspect languages, of which we give several examples. Using this framework, it is also possible to write programs that use aspects written in multiple aspect languages, expressed in terms of the interpreter framework. Finally, we present a powerful composition infrastructure that supports the definition of a range of composition mechanisms, such as different styles of inheritance, but also aspect-based or domain-specific composition mechanisms. The infrastructure is defined in terms of a language that defines no fixed composition semantics, but provides a generic mechanism for constructing composition mechanisms from primitives that are expressed as rst-class objects