[Boost-users] [signals] Chaining slots

Hello, I'm using Boost.Signals to implement Deferreds (http://twistedmatrix.com/projects/core/documentation/howto/defer.html). An important feature of Deferreds is the hability to chain callbacks. Speaking of Signals, I want a way to call slots using args from previous slots calls. For example: float square(float x) { return x*x; } float sum1(float x) { return x+1; } boost::signal sig; /* do some magic here */ sig.connect(&square); sig.connect(&sum1); sig.connect(&square); // sig(2) should call square(sum1(square(2))) std::cout << sig(2) << std::endl; I want the example to output 25 ( (2**2)+1)**2) Any ideas on how to implement this? Thanks, Allan Douglas