scleary@jerviswebb.com wrote:

I think the problem is in the definition of Select2ndRef; if you use: template<class pair_type> struct Select2ndRef { typedef pair_type argument_type; typedef typename pair_type::second_type result_type;

result_type & operator()(pair_type & source) const { return source.second; } }; then your code will compile.

This has to do with an unusual meaning of "result_type" for projection iterator adaptors.

Excellent, that seems to work fine. I've renamed Select2ndRef as Project2nd for use in such cases in the future <g> -- AlisdairM