Hello, I'm happy to announce the availability of the post-review version of Boost.Flyweight: *Online docs:* http://tinyurl.com/2sstyr http://svn.boost.org/svn/boost/sandbox/flyweight/libs/flyweight/index.html *Download as .zip:* http://tinyurl.com/hrdm6 http://www.boost-consulting.com/vault/index.php?&direction=0&order=&directory=Patterns *Check out from SVN:* https://svn.boost.org/svn/boost/sandbox/flyweight *Tested with:* MSVC++ 8.0 and GCC 3.4.4. Compilation reports most welcome. Older compilers like MSVC++ 6.5 are no longer supported. *What's new:* I've tried to address most of the suggestions and comments raised during the review. The two most important changes are: 1. Alberto Barbati's insightful review has led to the introduction of so-called key-value flyweights (http://tinyurl.com/5mnwjp ). This type of flyweights is meant for the situations where constructing the underlying type is expensive and must be avoided except if absolutely necessary. I think the design is robust enough and covers the variants (inner/outer key) that arose during the discussion with Alberto. 2. A comprehensive performance section is provided (http://tinyurl.com/5ap5kt ). *What's pending* 1. Some of the suggestions given at the review, like reducing intermodule_holder to static_holder when permissible (Vicente Botet) or studying read/write locking policies are still pending or have been postponed to later releases of the library. I felt the current state is sufficiently robust for publication. 2. Serialization support is currently broken, pending the resolution of a proposed feature to add to Boost.Serialization (run-time archive helpers). I'd be very grateful if you can take a look at the post- review version of Boost.Flyweight (specially if you were a reviewer), test it and comment on it, with emphasis on the new features like key-value flyweights. If people are happy with this revision my target release for inclusion will be Boost 1.38. Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo