Richard Newman <richard@cdres.com> writes:
So, the new current thinking is that std::accumulate is Better than simple while-loops that walk through elements which is still Bad. However, boost::bind under std::accumulate is Worse. At this point, the best advice is that one should use std::accumulate whenever simple accumulations are needed. However, once one has to start involving boost::bind on 1+-ary functions or anything else that requires new run-time function redirection, then retreating back to while-loop is a better performance solution.
This all depends on your compiler's optimization capabilities. If the compiler can't detect that the value of the function pointer is known at compile-time, then yes, bind will cost you. Similarly, if it can't do the small object optimization, transform_iterator may cost you. This is the unfortunate problem of abstraction penalty in C++. If you want optimal performance, you can either write low-level code, improve your compiler, or switch to a language that supports guaranteed optimization (see http://osl.iu.edu/~tveldhui/). Cheers, -- Dave Abrahams Boost Consulting http://www.boost-consulting.com