From the webpage [1
]: "Frag is a highly flexible object-oriented Tcl extension written in pure Tcl. It is intended as a configuration and composition language for components written in other languages, such as Java, C, and C++. Frag runs in Tcl and Jacl."
By Uwe Zdun
-- possibly connected to XOTcl
- Uwe Zdun. Tailorable language for behavioral composition and configuration of software components. Computer Languages, Systems & Structures, 32(1):56-82, April 2006. 
(You may need an academic Elsevier/ScienceDirect subscription to read that article). (Not to mention a time machine.) (NEM 16 Dec 2005
: Indeed, but that is the date given on the site...)