NetNews Usenet Archive 1992 #26/NN_1992_26.iso/spool/comp/lang/cplus/16100

Text File | 1992-11-11 | 1.6 KB | 40 lines

Newsgroups: comp.lang.c++
Path: sparky!uunet!boulder!happy.colorado.edu!srheintze
From: [e-mail]
Subject: Nested Classes vs. Class Specialization
Message-ID: <[e-mail]>
Lines: 27
Sender: [e-mail] (The Daily Planet)
Nntp-Posting-Host: happy.uccs.edu
Organization: University of Colorado, Boulder
Date: 11 Nov 92 10:28:16 MDT
Lines: 27


There seems to be a great benefit in using nested classes:  less
chance of name space collision.

For example, if we are creating a List class whose implementation consists
of a class for a list head and a link or node class, there is merit to
embedding or nesting the node class inside the List class.

However, suppose we use template classes.  Suppose we want to do template class
specialization as discussed in Stan Lippman's "C++ Primer" 2nd edition. For a
List class, we probably only want to  specialize the node class.

When experimenting with nested template classes on Borland C++ v3.1, I could
not figure out how to use nested template classes with specialization without
respecifying the entire List class. This, of course, defeats the purpose of
template class specialization.

I therefore conclude that it is impossible to get the best of both worlds.
For non-template classes, we want nested class but for template classes that
might be specialized, we do not want nested classes.

Can someone confirm this observation? Can someone figure out how to do
template class specialization of a Node class nested inside a List class
without respecifying the entire List Class?

            Thanks,
                    Sieg