Reverse Callback Templating
Many programmers know of the two main systems of templating. One embeds actual source code into the template. The other provides a mini language with loops, conditionals, and other control structures. There is a third way -- a reverse callback system. James Robson explains this best-of-both-worlds approach by demonstrating Perl's Template::Recall module.
Link: http://www.perl.com/pub/a/2008/03/14/reverse-callback-templating.html?CMP=OTC-BD0016219291&ATT=Reverse+Callback+Templating