Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!rutgers!att!westmark!mole-end!mat
From: mat@mole-end.UUCP (Mark A Terribile)
Newsgroups: comp.lang.c++
Subject: MI and namespaces
Keywords: MI namespaces
Message-ID: <192@mole-end.UUCP>
Date: 18 May 89 03:54:20 GMT
Organization: mole-end--private system.  admin: mole-end!newtnews
Lines: 35

Does anyone else have a feeling of possible impending doom lying around
the corner somewhere near MI?

Let's say that one of my various base classes (Ba) has a void Ba::reverse() .
I also have a base class Bb, and one day into one of *its* base classes
(Bbb, let us say) I add a base class which as a Bbb_b::reverse() .  I have
now created an ambiguity.  It's not clear to me that I can solve anything
by making one of the base classes private, and I don't really want to do
that anyway.  All I want to do is prevent Bb_b::member_xyz from being
IMPLICILTY visible and from being able to cause an ambiguity.

In other words, I want Bb_b::member_xyz to be visible in my ``most derived''
class as  Bb_b::member_xyz  but *not* simply as  member_xyz .  Moreover, I may
have another  member_xyz  which I *do* want to be able to refer to without
qualification.

Making the base class private and making public only the members you mean to
use may or may not solve the problem, depending on whether invisible private
members can create an ambiguity with visible ones.  (I've heard it both ways,
most recently that they can.  Will some very knowledgable person please
straighten me out?)

I fear that inheriting from lots and lots of base classes to get a variety of
capabilities is almost sure to lead, sooner or later, to enough ``print''s and
``dump''s and ``debug''s and ``verify''s that we are either going to begin
prefixing these names with the class qualifer out of habit or we are going to
prepend the class's name to the member name we would like to use.  This will
indicate (to me at least) that the name space controls we have are inadequate.
(This fear was reinforced today by my superior, who described the chaos that
occurs when namespaces are merged without controls as ``unstructured global
goto's.''  I share this bogey with someone, at least.)
-- 

 (This man's opinions are his own.)
 From mole-end				Mark Terribile