Re: Efficiency of single inheritance

From:
Pete Becker <pete@versatilecoding.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Sat, 3 Mar 2007 11:51:50 CST
Message-ID:
<1OednTU6v6YZDHTYnZ2dnUVZ_rWnnZ2d@giganews.com>
Davin Pearson wrote:

On Mar 1, 5:30 am, Markus Moll <markus.m...@esat.kuleuven.be> wrote:

Hi

Davin Pearson wrote:

I recently read a book that was cancelled from the University of
Canterbury library called: "Object Oriented Programming in Oberon-2"
by Hanspeter M\"ossenb\"ock. One sentence in this book that stands
out
for me is this one:
"Multiple inheritance also leads to less efficient code. For example
in C++ a method invocation causes additional runtime costs because of
the overhead involved with multiple inheritance --- even if the
program uses only single inheritance." (from page 109)

Care to explain? Otherwise it's just something that someone wrote in
some book.


Something that I accidentally omitted from my posting
is that Mossenbock cited the following reference
to justify his statement:

Stroustrup, B.: Multiple Inheritance for C++.
Proceedings EUUG Spring Conference, Helsinki,
May 1989.


There's a big difference between "I chose a 'sub-optimal' implementation
because it was more portable" and "in C++ a method invocation causes
additonal runtime costs ... even if the program uses only single
inheritance." The first is a statement about a particular implementation
(and remember, this was cfront, which generates C code, so portability
of the generated code was important) and the second is a general
statement about the language. Non sequitur.

--

    -- Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com)
Author of "The Standard C++ Library Extensions: a Tutorial and
Reference." (www.petebecker.com/tr1book)

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