This approach is sometimes referred to as literate programming. Emacs's org-babel package implements it for a variety of languages but only within org-mode fil

This approach is sometimes referred to as literate programming. Emacs's org-babel package implements it for a variety of languages but only within org-mode files (.org). You might be able to find a 3rd party package/script that works for you or you might find it easy to write/modify existing scripts depending on your particular use case.