Description:

[incr Tcl] is an object-oriented extension of the Tcl language. It
was created to support more structured programming in Tcl. Tcl scripts
that grow beyond a few thousand lines become extremely difficult to
maintain. This is because the building blocks of vanilla Tcl are
procedures and global variables, and all of these building blocks
must reside in a single global namespace. There is no support for
protection or encapsulation.

[incr Tcl] introduces the notion of objects. Each object is a bag
of data with a set of procedures or "methods" that are used to
manipulate it. Objects are organized into "classes" with identical
characteristics, and classes can inherit functionality from one
another. This object-oriented paradigm adds another level of
organization on top of the basic variable/procedure elements, and
the resulting code is easier to understand and maintain.