I won't get into the debate of whether headers are required; it feels like something that's more personal preference, like the One True Bracket Placement Method

I won't get into the debate of whether headers are required; it feels like something that's more personal preference, like the One True Bracket Placement Method. I will say that when it comes to well-documented code, your constraint is less the language than the people who make the code in the first place. Every non-header language I work with has at least one piece of automatic documentation parser that will grab the comment block directly above the method declaration and turn it into an easily-readable API. (I will note that for me personally, I prefer to keep well-commented and documented code in the one file, instead of needing to do odd window splits or jumping between open files to make sure my method declarations are in sync with my implementations. Header files seem, to me, to fly in the face of idea of not copy-pasting code-- function definitions that have to be modified by hand in multiple places just feel wrong.)