in reply to OT: Templating solutions - cross language rfc
Don't write a new one. If you really need something that has identical syntax and abilities in multiple languages, go with XSL. You can make it behave somewhat like HTML::Template if you try. Maintaining your own templating system in 4 languages (or even 3, if you start by porting an existing one) is hopeless. It's guaranteed to be lacking in features compared to the other choices.