Point of Departure
There are other open-source implementations of signals and slots, similar to the Qt QObject model. One is called xlobject (available at http://sourceforge.net/projects/xlobject). In contrast to Qt, it does not require any moc-style preprocessing, but instead relies heavily on templates, so it is only supported by modern (post-2002) C++ compilers. The boost library (available from http://www.boost.org) also contains an implementation of signals and slots.