Sigh, I was commenting in the repo, not in the PR. Here's a run down:

@gidden -
I can't seem to find where this macro is used in either this PR or the cycamore companion..

@gidden -
also, how do we feel about comments for macros? this is effectively a function that gets expanded, and we require comments for non-basic functions.

@rwcarlsen -
This isn't used anywhere. I was just experimenting with a bit of automation with the extern'd constructor functions we require module developers to manually add. It wasn't originally meant to be a part of this PR, but if we like the idea, I can add a doc comment.