Hi James, is it possible to have a look inside ? Rebinding template arguments sounds interesting (although I find the order of the parameters a bit strange). I could imagine cases where this is useful (for example making a std::{container}<type> a std::{container}< proxy<type> >). Jonathan Turkanis wrote a small lib for decomposing and synthesizing member function / function types, which covers the function part of your library. [ see http://thread.gmane.org/gmane.comp.lib.boost.devel/111645 ] I am currently working on some internal refinement of this, so I am curious to see how you implemented the function part. ( If it inspires my code your work will be acknowledged, of course. ) As I said in the thread referenced above I don't really know any real world applications for the synthesis part of it - same thing with the function part of your library. Regards, Tobias