Multics addressed that, back before Unix existed, as it needed to support controlled change.
I've used it for avoiding "flag days" in new software whose API was still mutating, which sounds a lot like this case
--dave (who typed Paul's talk in) c-b
Copyright © 2018, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds