The activity of design involves the decomposition of problems into subproblems and the development and evaluation of solutions. In many cases, solution development is not done from scratch. Designers often evoke and adapt solutions developed in the past. These solutions may come from an internal source, i.e. the memory of the designers, and/or from an external source. The goal of this paper is to analyse the characteristics of the cognitive mechanisms, the knowledge and the representations involved in the code reuse activity performed by experienced programmers. More generally, the focus is the control structure of the reuse activity. Data collected in an experiment in which programmers had to design programs are analyzed. Two code reuse situations are distinguished depending on whether or not the processes involved in reuse start before the elaboration of what acts as a source-solution. Our analysis highlights the use of reasoning from a schema and from an analog in the code reuse activity.