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,FREEMAIL_FROM
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Thread: 109fba,cd8ed9115942852f
X-Google-NewGroupId: yes
X-Google-Thread: 103376,b92b95c9b5585075
X-Google-NewGroupId: yes
X-Google-Attributes: gid4f1905883f,gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news2.google.com!news.glorb.com!news-out.readnews.com!transit3.readnews.com!s09-11.readnews.com!unm2.readnews.com.POSTED!not-for-mail
X-Trace: 
 DXC=b2I>fTn7P`LM=?cF8X300BTLaYZ5A`]3G]UVm4ab0o;Ok`R^3PKYWgCSUXD^Wd\CQL`LSM[oHHnYOi4hBgTdKg6C39AYQN6>3K@=g7J85eQVa@
X-Complaints-To: abuse@usenet-news.net
Date: Fri, 12 Aug 2011 09:15:22 -0400
From: Hyman Rosen <hyrosen@mail.com>
User-Agent: Mozilla/5.0 (Windows NT 5.1;
 rv:5.0) Gecko/20110624 Thunderbird/5.0
MIME-Version: 1.0
Newsgroups: comp.lang.c++,comp.lang.ada
Subject: Re: Why use C++?
References: <fb9f787c-af06-427a-82b6-b0684e8dcbc5@s2g2000vby.googlegroups.com>
 <j1kaj8$dge$1@adenine.netfront.net>
 <1e292299-2cbe-4443-86f3-b19b8af50fff@c29g2000yqd.googlegroups.com>
 <j1tha5$11q5$1@adenine.netfront.net>
 <1fd0cc9b-859d-428e-b68a-11e34de84225@gz10g2000vbb.googlegroups.com>
 <9ag33sFmuaU1@mid.individual.net> <j1v17b$h98$1@munin.nbi.dk>
 <1d8wyhvpcmpkd.ggiui9vebmtl.dlg@40tude.net> <j203cu$q97$1@dont-email.me>
 <150vz10ihvb5a.1lysmewa1muz4$.dlg@40tude.net> <j20cif$dr6$1@dont-email.me>
 <1q4c610mmuxn7$.1k6s78wa0r8fj.dlg@40tude.net> <j22c68$2m7$1@dont-email.me>
 <4e44e50a$0$7619$9b4e6d93@newsspool1.arcor-online.net>
In-Reply-To: <4e44e50a$0$7619$9b4e6d93@newsspool1.arcor-online.net>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Message-ID: <4e45276d$0$13269$a8266bb1@newsreader.readnews.com>
Organization: readnews.com - News for Geeks and ISPs
NNTP-Posting-Host: 0618e502.newsreader.readnews.com
Xref: g2news2.google.com comp.lang.c++:92617 comp.lang.ada:21541
Date: 2011-08-12T09:15:22-04:00
List-Id: <comp.lang.ada>

On 8/12/2011 4:32 AM, Georg Bauhaus wrote:
> #define RGB_LIMIT 3
>
> typedef unsigned char Intensity;
> enum RGB {Red, Green, Blue};
> typedef Intensity Pixel[RGB_LIMIT];

I might do this instead as

     typedef unsigned char Intensity;
     enum RGB_Index { Red, Green, Blue, N_RGB_Index };
     typedef Intensity Pixel[N_RGB_Index];

which avoids the need for a macro and ties the number of
intensities in the array directly to its enumerated index.

> switch (1) { case 0: break; case CHAR_BIT == 8: break; }

Oh, that's cute! It's going right into my bag of tricks :-)
You don't need the breaks, though:

     switch (1) { case 0: case CHAR_BIT == 8: ; }

And with C++, you don't need executable code:

// Probe template
template <bool tf> struct probe { };
template <> struct probe<true> { typedef int t; };

// test for 8-bit char
typedef probe<CHAR_BIT == 8>::t is_char_8_bit;

> If I am a beginner, what is the number of technicalities I
 > must know it order to understand the second way of declaring
 > things?

A few; of course, when I was a complete Ada beginner (not that
I'm much more than that now) I was always thrown by the use of
apostrophes as attribute designators. When I see

     for Intensity'Size use 8;

it makes me want to go off searching for where the string ends
and trying to figure out what's going on. I also don't know that
a beginner finds the notion of an enumerated type declared as an
array index to be immediately obvious.

> (I'll leave out that the declare-like-used rule in typedef is
> confusing many. Maybe that's because the typdef-ed name isn't in some
> fixed position in the typedef.)