Version 18 of expand

Not to be confused with {expand} (now {*}).

A macro and/or template processor written in Tcl for Tcl, by William Duquette. See http://www.wjduquette.com/expand/index.html for its homepage.

The central algorithm of the expand tool was repackaged as expander in Tcllib. See http://tcllib.sourceforge.net/doc/expander.html

This is a useful tool for conversion of tcl-based documents into other formats. The range of applications include

Generation of website with uniform look & feel. See the homepage [L1 ] of the expand author, or AK's memchan website at SourceForge [L2 ] for examples of this.
Conversion of manpages in a tcl-based markup to HTML, nroff, TMML, etc. See doctools.
Generation and setup of Makefiles for an extension based upon a template.
Provide a generic support to update a set of files depending on single definition file (tcl script).

All of this falls under the broad category of Template and Macro processing.