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Scientific Programming
Volume 21 (2013), Issue 1-2, Pages 43-61
http://dx.doi.org/10.3233/SPR-130362

Template Metaprogramming Techniques for Concept-Based Specialization

Bruno Bachelet,1,2 Antoine Mahul,3 and Loïc Yon1,2

1Clermont Université, Université Blaise Pascal, LIMOS, BP 10448, F-63000 Clermont-Ferrand, France
2CNRS, UMR 6158, LIMOS, F-63171 Aubière, France
3Clermont Université, Université Blaise Pascal, CRRI, F-63000 Clermont-Ferrand, France

Copyright © 2013 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In generic programming, software components are parameterized on types. When available, a static specialization mechanism allows selecting, for a given set of parameters, a more suitable version of a generic component than its primary version. The normal C++ template specialization mechanism is based on the type pattern of the parameters, which is not always the best way to guide the specialization process: type patterns are missing some information on types that could be relevant to define specializations. The notion of a concept, which represents a set of requirements (including syntactic and semantic aspects) for a type, is known to be an interesting approach to control template specialization. For many reasons, concepts were dropped from C++11 standard, this article therefore describes template metaprogramming techniques for declaring concepts, modeling relationships (meaning that a type fulfills the requirements of a concept), and refinement relationships (meaning that a concept refines the requirements of another concept). From a taxonomy of concepts and template specializations based on concepts, an automatic mechanism selects the most appropriate version of a generic component for a given instantiation. Our purely library-based solution is also open for retroactive extension: new concepts, relationships, and template specializations can be defined at any time; such additions will then be picked up by the specialization mechanism.