Despite that reuse libraries are now well adopted during software development step, software evolution step is not yet covered by this kind of beneficial approach. In this paper we present the "evolution shelf", a generic infrastructure to achieve for-reuse and by-reuse techniques within the field of software evolution. The basic idea behind that is to propose and encourage the reuse of recurring and reliable evolution expertises to achieve the structural evolution of a software system at the architectural level. For that purpose, the shelf assists architects in classifying, storing and selecting reusable architectural evolution operations. The underlying concept that we propose to capitalize the expertises is called "evolution style" and it mixes a syntactic and a semantic description format. These ideas form a core for a long-term vision in which it is possible to build a business model of evolution-of-the-shelf (EOTS) with the special objective to decrease the efforts and the risks related to the evolution activities.