Incr Tcl adds object-oriented programming facilities to Tcl. It was
NOT designed as another whiz-bang, object-oriented programming
language. It is patterned somewhat after C++. It was designed to
support more structured programming in Tcl. Scripts that grow beyond a
few thousand lines become extremely difficult to maintain. [incr Tcl]
attacks this problem in the same way that any object- oriented
programming language would, by providing mechanisms for data
encapsulation behind well-defined interfaces.