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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,a6fe9ef21ba269dc
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news2.google.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.bt.com!news.bt.com.POSTED!not-for-mail
NNTP-Posting-Date: Mon, 16 Aug 2010 16:31:53 -0500
From: Brian Drummond <brian_drummond@btconnect.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada Smileys in C++ lib Conversion
Date: Mon, 16 Aug 2010 22:39:22 +0100
Reply-To: brian@shapes.demon.co.uk
Message-ID: <kt9j66l9a9har44trma2iu3j1ff16lalfi@4ax.com>
References: <9b88e5a4-c588-4997-ad5c-2efa216fe4f4@a4g2000prm.googlegroups.com>
 <b05a83d9-fac1-45cb-91c5-f99516ca27f2@k10g2000yqa.googlegroups.com>
 <95tc66hjv3stdk0nhdv9o46e5l2ecdog5j@4ax.com>
 <b5965b85-39fd-434c-b693-f6760f949b2f@x21g2000yqa.googlegroups.com>
 <a5fe665sg9vhdh80d5p8cqu6v3dlpfk5to@4ax.com>
 <15cdcb9e-3747-48e3-9be0-8829dfbcc3c8@w30g2000yqw.googlegroups.com>
 <mabi66ph5p38pqidk3rcal3bopvbgq155h@4ax.com>
 <4915efdd-46ba-436b-b989-6067ce5a03bf@i31g2000yqm.googlegroups.com>
X-Newsreader: Forte Agent 1.7/32.534
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Usenet-Provider: http://www.giganews.com
X-AuthenticatedUsername: NoAuthUser
X-Trace: 
 sv3-QBoaHUKMi7aInopW2y6GaVOGXDfrgEKvlFzQ9YeUKkF40UaaC2UNroC0DtR5ucR+deBR0TEqm4Qc5y/!VPmY9tsblSDAVHE4JeI/gB680Yk4GedVUT/EcWWifNTTAf56X9aEx9wHHbGbCzq44PyydSC6iuk2!O6k=
X-Complaints-To: abuse@btinternet.com
X-DMCA-Complaints-To: abuse@btinternet.com
X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers
X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint
 properly
X-Postfilter: 1.3.40
Xref: g2news1.google.com comp.lang.ada:13433
Date: 2010-08-16T22:39:22+01:00
List-Id: <comp.lang.ada>

On Mon, 16 Aug 2010 05:39:34 -0700 (PDT), Maciej Sobczak
<see.my.homepage@gmail.com> wrote:

>On 16 Sie, 14:30, Brian Drummond <brian_drumm...@btconnect.com> wrote:

>> So a "const" is not constant, says the compiler.
>
>The above is guaranteed to work by the C++ standard (nerds see
>5.19/1).

And it does work in C++. 
(It was clear I was talking about C, yes?).

>The problem will be when the initializer for "size" above will indeed
>be a function call - this would not be a constant expression, even
>though the object "size" is declared as const.
>The reason is that constant expression should always evaluate to the
>same value, whereas function calls are not required (and cannot be
>verified) to do so. 
... even though the function is only called once to initialise the const - and
it is a "pure function" in Ada or VHDL terms - and all its arguments are consts
(or even constants!). Does make me wonder what _can_ be verified in C++.

>So, there is a difference between a "constant expression" (roughly
>equivalent to Ada's "static expression") and a "const object".
>Array bounds require constant expression.

So we have - even in C++ - a const object that cannot be used 
where a constant expression is required.

Interesting, Thanks.

To get back almost on-topic, I am frequently amazed in Ada, after years of
bruising by various {}-languages, how often I can program from the BNF, (i.e.
"the BNF doesn't stop me doing this, but surely it can't be THAT simple..." 
and it just works. 

- Brian ... smiling