The CLASSIC library is a C++ class library which provides services for building portable accelerator models and algorithms for their analysis. This paper describes the motivations behind the CLASSIC library and its main features. It shows how this library can be used in a large accelerator design program like the new version 9 of MAD written in C++. The possibilities are illustrated by presenting some new developments in MAD version 9, like sophisticated matching features with simultaneous matching of two rings.The major part of the CLASSIC library is now implemented. Its source code and some preliminary documentation are available from the author
