FWIW, yes, I also build my applications at MSVC warning level 4. But in this particular case, I don't think that this specific warning needs to be pragma'd off! The warning reported by ticket #1704 says: "boost/any.hpp(130) : warning C4512: 'boost::any::holder<ValueType>' : assignment operator could not be generated" <http://svn.boost.org/trac/boost/ticket/1704> Wouldn't it be preferable to explicitly disallow the assignment of any::holder? Just by adding a private and unimplemented copy assignment operator? When doing so, we'll get rid of the warning automatically. I don't think any::holder needs to be CopyAssignable. any::holder is only accessible by boost::any, and its friends unsafe_any_cast, and unsafe_any_cast. Neither of them uses the assignment of any::holder. Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center