Hi all, I am trying to use a callback mechanism for logging in my app. I thus have a class with : class coordinates_converter { public: coordinates_converter(int id); ~coordinates_converter(); void register_error_callback (const boost::function<void(std::string message)> &callback ) { _error_callback = callback; } private: boost::function<void(std::string message)> _error_callback; } Now, if I want to register a log error callback in another object instance, how should I do this? Cannot find the right syntax ... void another_class::do() { acute_coordinates_converter* converter = new coordinates_converter(2154); converter->register_error_callback( boost::bind(&another_class::log_error, converter, _1) ); } where log_error is a Qt SIGNAL: signals: void log_error(const std::string& error); Hope you could help. Rehads, Olivier