>Interface inheritance good. In general, implementation inheritance bad.

I'm with you that adding functionality through aggregation
is better than adding oodles of layers in the single inheritance vfp/java/c# offer.

But interfaces IMHO are just a poor man's version of mixin possibilities
offered by MI systems - a PITA necessitated by the language design.
And no, diamond problems are not the norm, but the exception (like real diamonds...)

Have programmed in a MI capable system/language,
preferably something easier than C++ ?

curious

thomas