Hi, I just downloaded the newest boost library 1.33.1 and compiled the "maximum.cpp" example from the Signals library, which goes like this: #include <algorithm> #include <iostream> #include <boost/signals/signal2.hpp> template<typename T> struct maximum { typedef T result_type; template<typename InputIterator> T operator()(InputIterator first, InputIterator last) const { if (first == last) throw std::runtime_error("Cannot compute maximum of zero elements!"); return *std::max_element(first, last); } }; int main() { boost::signal2<int, int, int, maximum<int> > sig_max; sig_max.connect(std::plus<int>()); sig_max.connect(std::multiplies<int>()); sig_max.connect(std::minus<int>()); sig_max.connect(std::divides<int>()); std::cout << sig_max(5, 3) << std::endl; // prints 15 return 0; } As stated, the correct result would be 15 but the output really is 8. However, when I print the values via std::copy(first, last, std::ostream_iterator<T>(std::cout, " ")); I get "8 15 2 1 ", which means that the values are calculated correctly. This error occurs with Microsoft Visual Studio 2005 (8.0) as well as MinGW 3.4.2. I even tried replacing std::max_element() with my own function, which expectedly didn't help. Seems like a bug to me, but I can't track it down. Could it be some issue with copying the iterator? Benjamin Winkler