John Femiani wrote:
What is not lightweight about the get<0>(pt) syntax? Doesn't it compile away? Is the issue a dependency on another library -- because the get<0>(pt) syntax seems really easy to provide without bothering with Fusion.
i.e. template <int Index> float get(MyPoint & p) {return p[Index];} OR template <> float get<0>(MyPoint & p) {return p.x;}
Dependency is indeed an issue. Sure you can get by with the simple interface above. I think that's the barest minimum. Perhaps the next step is to provide an optional mapping to fusion when explicitly specified by the client. This would be desirable in cases where the client directly or indirectly uses fusion anyway. The advantage in making your structs full fledged fusion sequences will become apparent when you go into more generic programming. The simplest would be, say, iterating to all the (possibly heterogeneous) dimensions and applying some generic algorithms on them. All that being said, while taken as a whole, fusion might indeed be big, the core code that deals with iterators and adopting is rather lightweight. You only pay for what you use. The iterators and adapters are only two cents a piece ;-) Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net