Path: utzoo!utgpu!water!watmath!clyde!att!ulysses!hector!ekrell
From: ekrell@hector.UUCP (Eduardo Krell)
Newsgroups: comp.lang.c++
Subject: Re: Can we hide the private part of a class ?
Keywords: header dependency, efficiency.
Message-ID: <10687@ulysses.homer.nj.att.com>
Date: 3 Oct 88 20:46:02 GMT
References: <1368@cumulus> <10681@ulysses.homer.nj.att.com> <1369@cumulus>
Sender: netnews@ulysses.homer.nj.att.com
Reply-To: ekrell@hector.UUCP (Eduardo Krell)
Organization: AT&T Bell Laboratories
Lines: 22

In article <1369@cumulus> hsu@cumulus.UUCP (Yung-Kao Hsu) writes:

>The problem you mentioned above really only hit half of the target. If the
>sizeof() was used, the data type involved really is not private as far as
>I can see.

I didn't explain myself. I meant to say that anytime the size of the class
is needed (e.g., when you generate an instance of the class), that module
will have to be recompiled.

You don't have to use sizeof() directly, but the compiler will need it
to generate the right argument for malloc() when you create an object
of that class.

And there's more. You can move members around and add/remove private
members.  That could change the relative offsets of members in the
class. A program that was using object->member now needs to be
recompiled because the offset of "member" might have changed...
    
Eduardo Krell                   AT&T Bell Laboratories, Murray Hill, NJ

UUCP: {att,decvax,ucbvax}!ulysses!ekrell  Internet: ekrell@ulysses.att.com