Zeuthen: Writing a C library, part 1

Using environment variables to pass information directly from outside user to a library has a long-established and fairly robust history. In particular for things like debugging, path and locale setting. I agree that libraries should *also* be able to be configured via API params in case the calling program has a need to set the same things, but if the library also knows to look in the environment it means I can type LC_ALL=de_DE and any glibc using program will get it right, instead of only those where the outer program bothered to allow me to set the language. So I disagree with your recommendation there.