An argument pro component-based software development is the idea of constructing software systems by assembling preexisting components instead of redeveloping similar or identical functionality always from the scratch. Unfortunately, integrating existing components practically means reuse (i.e., adaptation and use) rather than use only, which makes a clean, ideal component-based development hard to realize in practice. Product line engineering, however, is an approach that tackles this problem by making components systematically as generic as needed for a particular product family and thus allows components to be reused easily within a family context. Making a component generic means a component covers variabilities among systems in the family and thus that its implementation must consider variabilities. In this paper, we describe a process for implementing generic product line components and give an overview of variability mechanisms at the implementation level. The process, as well as the described variability mechanisms, is illustrated by a running example, a generic test component.
