I just tried using the lambda library for the first time. Here's what came out of it, after some struggle: #include <boost/lambda/lambda.hpp> #include <vector> #include <numeric> using namespace boost::lambda; struct X { X() : count(1) {} unsigned long count; }; std::vector<X> xs(10); unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, _1 + (&_2) ->* &X::count); This program adds up the "count" members in a vector of X objects. Now, no offense intended, but this is nasty. There's just too much extra syntax required for something so simple, plus you have to make the type into a pointer just so you can dereference it Before I realized I needed to take the address of _2, I had: unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, _1 + _2 ->* &X::count); which is only slightly better (but incorrect). I realize that I can use bind: unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, _1 + bind(&X::count,_2)); but that's slightly counter-intuitive since the order of the target object and its member pointer are reversed. It'd be nice to allow something like: unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, _1 + _2.at(&X::count)); while if _2 were to refer to a pointer type, we could say: unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, _1 + _2->at(&X::count)); -- Dave Abrahams Boost Consulting www.boost-consulting.com