Incr Tcl

incr Tcl (commonly stylised as  [incr Tcl] , and often abbreviated to itcl) is a set of object-oriented extensions for the Tcl programming language. It is widely used among the Tcl community, and is generally regarded as industrial strength. Its name is a pun on "C++". Itcl implementations exist as both a package that may be dynamically loaded by a Tcl application, as well as an independent standalone language with its own interpreter.

Namespace support
Itcl allows namespaces to be used for organizing commands and variables.

Example:

C code integration
Itcl (like Tcl) has built-in support for the integration of C code into Itcl classes.