libsigc++ implements a typesafe callback system for standard C++. It allows you to define signals and to connect those signals to any callback function, either global or a member function, regardless of whether it is static or virtual.
http://libsigc.sourceforge.net/
This installer guides you through the steps necessary to install libsigcxx2 2.2.4.2 for Mac OS X. To get started, click Continue.