Reflection is a wide-ranging concept that has been studied independently in many different areas of science in general, and computer science in particular. Even in the sub-area of programming languages, it has been applied to different paradigms, especially the logic, functional and objectoriented ones. Partly because of different past influences, but also because researchers in these communities scarcely talk to each others, concepts have evolved separately, sometimes to the point where it is hard for people in one community to recognize similarities in the work of others, not to speak about cross-fertilization among them. In this paper, we propose a synthesis covering mainly the application of computation reflection to programming languages. We compare the different approaches and try to identify similar concepts hidden behind different names or constructs. We also point out the different emphasis that has been given to different concepts in each of them. We do not claim neither comp...

Building softwares in a concern oriented fashion can be splited in two main steps : first defining each concern separately (or reusing existing ones) and then composing (i.e. integrating) those concerns together. Among existing approaches to support this development scheme, we are interested in reflection. This interest is particularly motivated by the natural separation between functional and non-functional concerns provided by reflection. In this paper, we describe our approach based on reflection. We provide a solution to define and compose reusable non-functional concerns, while minimizing integration efforts. Keywords: Concerns Composition ; Concern Reuse ; Metaclasses ; Reflection ; Smalltalk. 1 Introduction Separation of concerns [Dij76] [HL95] is the foundation for the programming paradigm that we named Concern Oriented Programming (COP). This programming paradigm consists of separating concerns before composing (i.e. integrating) them to produce softwares. Once concer...