I was wondering the same thing. Perhaps he means all the extra "fire::" annotations one needs to put in place in function parameter lists as well as the ultimate dispatcher instatiating cpp macro? Really there is always at least 2.5 with the #include , later macro and annotations.

https://github.com/c-blake/cligen achieves the actual 1-line of code dream without extra annotations and even leveraging existing API documentation and even colorizing said rST docs in terminal generated help output. { Of course, that one line might be an "import cligen; dispatch(foo)" which is arguably denser than most people would format it. } One usually wants to add some per-parameter help, though, unless your parameter names are always much more descriptive than "x" and "y".