Beyond generic component parameters

Abstract

For flexible use in application contexts, software components should be parameterized, but also extended appropriately. Until now, there is no language mechanism to solve both problems uniformly. This paper presents a new concept, component hooks. Hooks are similar to generic component parameters but go some steps beyond. Firstly, they allow genericity on arbitrary program elements, leading to generic program elements. Secondly, they introduce an abstraction layer on generic parameters, allowing for structured generic parameters that bind several program elements together. Thirdly, if they are abstract set or sequence values, they can also be used to extend components. Lastly, since they only rely on a meta model they are a language independent concept which can be applied to all languages. Hooks form a basic parameterization concept for components written in languages with a meta model. For such languages, hooks generalize many well known generic language mechanisms, such as macros, semantic macros, generic type parameters, or nested generics. They also provide a basic concept to realize simple forms of aspect weavers and other advanced software engineering concepts.