Interface inheritance is broadly fine though, because it specifically lacks the conflation of "base class" and "derived class" code. The interface can be assumed to directly imply some invariants, and it's easy to see of any implementation whether it respects them. Everything is nicely localized.
I agree, but I didn't interpret the comment I was responding to as objecting to implementation inheritance as such, rather the contrary: they're objecting to an enormously wide category of OO designs which includes not only interface inheritance but also most, but not all, uses of implementation inheritance; for example, the Smalltalk-80 design that lumps inject and select into some abstract base class for containers.
