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Date: 27 Dec 91 21:40:19 GMT
From: alice!bs@ucbvax.Berkeley.EDU  (Bjarne Stroustrup)
Subject: Re: Multiple Inheritance in Ada 9X
Message-ID: <22010@alice.att.com>
List-Id: <comp.lang.ada>

There is not to my knowledge any evidence that multiple inheritance
(as implemented in C++ or elsewhere) is particularly dangerous or where
used for real projects has caused any harm.

As with other features that are new to the majority of programmers there
has been quite a debate about multiple inheritance. My impression is that
most of the debate has been among language laywers and that much have been
misguided in that it has focussed on obscure points of language law and
at best weakly supported by experience or notions of programming style.

As noted by Dan Weinreb, C++'s notion of MI is less powerful that that of
CLOS. That was understood at the time and accepted as something that was
probably a necessesary price to pay for C++'s static type checking and
run-time efficiency. 

Somebody used the phrase ``bolted on'' about C++'s multiple inheritance
facility. I consider that a typical misunderstanding/misrepresentation.
FYI: Multiple inheritance was first considered very early on in the
development of C++ (about 1982) but the actual introduction was delayed
until 1986 when I felt I had enough understanding, experience,and time
to tackle the issue.

MI in C++ and elsewhere isn't perfect and it isn't a panacea, but it works
and it makes some styles of programming noticeably more convenient and
less obscure. Naturally, it can also be overused and misused, but basically
it works.