I came across the technique while reading Hanson's C interfaces & Implementations. By the way the book is a very good read (it abstracts and amplifies the techniques used in the creation of lcc). At least for books it seems quite useful. As far as using it for real in code, I don't know, you will have to teach your editor to put a link to code, and to present whatever is linked in-place in a different font say. Mean IDEs could even replace the code by a function! ;)