I believe that separating interface from implementation doesn't really solve the problem, it just shrinks it. E.g. what if you depend on two libraries that re-e

I believe that separating interface from implementation doesn't really solve the problem, it just shrinks it. E.g. what if you depend on two libraries that re-export classes from different versions of a third library? I think that if you truly want to solve the problem, you need to extend the definition of the fully qualified classname to include the notion of a breaking version reference. Kind of like what folks now sometimes do the hard way by encoding it into the package name. This would make it possible to directly address the two different versions from the same calling source file.