From Rosetta Code
This is an example of a library. You may see a list of other libraries used on Rosetta Code at Category:Solutions by Library.

TclOO is a library for Tcl 8.5, which provides access to the same object-oriented programming facilities as are built directly into Tcl 8.6. For backward compatibility, Tcl 8.6 also provides this package; this means that user code that needs an object system can just do: <lang tcl>package require TclOO</lang> See the TclOO page on the Tcler's Wiki for more information.

Works with: Tcl version 8.5