Yes, this was pretty common in Pascal. Also, Emacs uses comments to set file-local options. There's a long tradition of overloading comments to achieve metalin

Yes, this was pretty common in Pascal. Also, Emacs uses comments to set file-local options. There's a long tradition of overloading comments to achieve metalinguistic ends. JavaDoc and Doxygen are great examples. Even when handed a decent macro language with whizzy namespaces and a great DOM, I imagine that some people will still stoop to gross and convenient hacks.