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From: bothner@sevenlayer.cs.wisc.edu (Per Bothner)
Newsgroups: comp.lang.c++
Subject: Re: Nonvirtual base classes in MI
Message-ID: <1991Feb1.195420.26603@spool.cs.wisc.edu>
Date: 1 Feb 91 19:54:20 GMT
References: <1159@zinn.MV.COM> <1991Jan31.164927.3234@odin.corp.sgi.com>
Sender: news@spool.cs.wisc.edu (The News)
Reply-To: bothner@sevenlayer.cs.wisc.edu (Per Bothner)
Organization: University of Wisconsin--Madison
Lines: 16

In article <1991Jan31.164927.3234@odin.corp.sgi.com>, linton@sgi.com (Mark Linton) writes:
>I would like to echo the original question, as I also have not encountered
>a situation where I need non-virtual base classes.

Perhaps it should be emphasized that even if one doesn't
*need* non-virtual base classes, it may be reasonable
to use them anyway for efficiency reasons. The main example
is that of abstract base classes (or ones where the base
class is otherwise "constant.") If one has a class hierarchy
rooted in Object, it is undesirable to make Object a virtual
base class, since it would add an extra indirection to
*every virtual function call,* even for objects which
only actually inherit from Object along a single path.
-- 
	--Per Bothner
bothner@cs.wisc.edu Computer Sciences Dept, U. of Wisconsin-Madison