[nickelbox]

The macro would only be used to generate k for convenience. It could be all implemented in straight, macro-less C++98 in O(minutes).

My point was just that you can implement almost whatever you want (even without macros, they'll just expand the design space).

[joshuamorton]

I don't see how you could implement the (k.attr).for_(k) part. That's essentially an assignment, a macro could maybe convert it to a lambda, but I don't see how it would be done macro-free.