From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,703c4f68db81387d
X-Google-Thread: 109fba,703c4f68db81387d
X-Google-Thread: 115aec,703c4f68db81387d
X-Google-Thread: f43e6,703c4f68db81387d
X-Google-Attributes: gid103376,gid109fba,gid115aec,gidf43e6,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news3.google.com!news.glorb.com!newsread.com!news-xfer.newsread.com!nntp.abs.net!attws2!att542!ip.att.net!newsfeed3.global.lmco.com!svlnews.lmms.lmco.com!not-for-mail
From: "REH" <bogus@nowhere.net>
Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng
Subject: Re: [OT] Re: Teaching new tricks to an old dog (C++ -->Ada)
Date: Mon, 28 Mar 2005 13:51:02 -0500
Organization: Earth
Message-ID: <d29jmm$nak3@cui1.lmms.lmco.com>
References: <4229bad9$0$1019$afc38c87@news.optusnet.com.au>
 <1110032222.447846.167060@g14g2000cwa.googlegroups.com>
 <871xau9nlh.fsf@insalien.org>
 <3SjWd.103128$Vf.3969241@news000.worldonline.dk>
 <87r7iu85lf.fsf@insalien.org> <1110052142.832650@athnrd02>
 <hwciddo3rp1S@eisner.encompasserve.org>
 <e39403d5.0503100359.5c975706@posting.google.com>
 <1lr611thktbau$.1dj95z21h7l5v.dlg@40tude.net>
 <e39403d5.0503110005.6586fa3f@posting.google.com>
 <wccis3k1zq0.fsf@shell01.TheWorld.com>
 <kb9f41tmpibkirj29fu2golfsqpefikq6a@4ax.com> <1112022773.497341@athnrd02>
 <d298p3$mpp2@cui1.lmms.lmco.com> <1112026376.920221@athnrd02>
 <d29c80$mpp3@cui1.lmms.lmco.com> <1112034544.645999@athnrd02>
NNTP-Posting-Host: 158.187.64.144
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2800.1437
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441
Xref: g2news1.google.com comp.lang.ada:10088 comp.lang.c++:47649
 comp.realtime:1790 comp.software-eng:5426
Date: 2005-03-28T13:51:02-05:00
List-Id: <comp.lang.ada>


"Ioannis Vranos" <ivr@remove.this.grad.com> wrote in message
news:1112034544.645999@athnrd02...
> REH wrote:
>
> > Well, suppose your class contains a variable of type double, which on
some
> > systems is 8 bytes and requires 8 byte alignment.  The array you are
> > defining to hold the class is a character array, which only requires 1
byte
> > alignment.  If it is created with a 1 byte alignment, when you create
the
> > class in it using placement new, now the double is misaligned.
>
>
> But we can treat a double variable as a sequence of unsigned chars/plain
chars plus copy
> it byte by byte (char/unsigned char) to a new unsigned char/char sequence
and have an
> exact working copy of the original. So since we can do this for stand
alone
> doubles/sequences of doubles, then why can't we do this in the double
contained in a class
> case?
>
I never said you couldn't.  I was just pointing out that what you wrote was
not portable, and would not work for any arbitrary class.  Besides, why
would you incur the extra time and complexity of manually moving the data
back and forth, byte-by-byte instead of just insuring the correct alignment
and letting the compiler take care of it?