The real major issue with multiple inheritance is that only a few languages (Eiffel, for one) seem to require declaring invariants for each class. Then multipl

The real major issue with multiple inheritance is that only a few languages (Eiffel, for one) seem to require declaring invariants for each class. Then multiple inheritance is much cleaner because you can test constructor arguments against the union of these invariants before even hitting a constructor. Note that I’ve never used it, but it did strike me that this was “the” way to include multiple inheritance in a language. But for some reason (run time performance maybe?) no one else seems to have done it this way.