C++ library of generic design patterns

 Loki is a ("the"?) C++ library of generic programming techniques, containing
 flexible implementations of common design patterns and idioms. It is an
 essential library for modern C++ programming and exposes many cool features
 of the language.
 .
 The code accompanies the (non-free) book, _Modern C++ Design_ (Alexandrescu,
 2001), which goes into depth on the design of the library.