libpropc++ is a template library for properties in
C++ which can be used like 'widget.color = "red";' to change widget color. Values of several properties can be "bound together" so that when one property changes, others automatically change accordingly. Binding can be unidirectional or mutual, with a transforming functor, etc. A part of the functionality of libsigc++ (a C++ "signal programming", i.e. Observer Pattern, library) is reimplemented.
