incr Tcl 4.0.2
[incr Tcl] is the most popular object-orientation language extensions for Tcl. Its object model is comparable to C++, includes multiple inheritance, classes and instances, and property and method visibility modifiers. It simplifies Tcl/Tk application building, both desktop apps or games; and generally structuring code flow, or chaining classes to C and C++ code. It also comes with new [incr Widgets] and [incr Tk] for building complex and custom widgets.