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-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 109fba,e0a59694a441eb7b
X-Google-Thread: 103376,e0a59694a441eb7b
X-Google-Thread: fac41,e0a59694a441eb7b
X-Google-Thread: 1108a1,e0a59694a441eb7b
X-Google-Attributes: gid109fba,gid103376,gidfac41,gid1108a1,public
X-Google-ArrivalTime: 2004-04-23 09:45:48 PST
Path: 
 archiver1.google.com!news1.google.com!news.glorb.com!in.100proofnews.com!in.100proofnews.com!news-out.visi.com!petbe.visi.com!news.octanews.net!ash.uu.net!spool.news.uu.net!not-for-mail
Date: Fri, 23 Apr 2004 12:45:47 -0400
From: Hyman Rosen <hyrosen@mail.com>
User-Agent: Mozilla Thunderbird 0.5 (Windows/20040207)
X-Accept-Language: en-us, en
MIME-Version: 1.0
Newsgroups: comp.lang.c++,comp.lang.ada,comp.lang.eiffel,comp.object
Subject: Re: OOP Language for OS Development
References: <95db0572.0404142153.431fd058@posting.google.com>
 <566e2bfb.0404181753.2844342f@posting.google.com>
 <ytOgc.39006$zm5.17464@nntpserver.swip.net>
 <c67sgr$2e0$1@news5.svr.pol.co.uk> <4088D574.2020503@tele2.fr>
 <c6ap5j$1nh$1@newsg1.svr.pol.co.uk> <c6bfs3$ed7$1@a1-hrz.uni-duisburg.de>
In-Reply-To: <c6bfs3$ed7$1@a1-hrz.uni-duisburg.de>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Organization: KBC Financial Products
Message-ID: <1082738747.300309@master.nyc.kbcfp.com>
Cache-Post-Path: master.nyc.kbcfp.com!unknown@nightcrawler.nyc.kbcfp.com
X-Cache: nntpcache 3.0.1 (see http://www.nntpcache.org/)
NNTP-Posting-Host: 204.253.250.10
X-Trace: 1082738747  28679 204.253.250.10
Xref: archiver1.google.com comp.lang.c++:31301 comp.lang.ada:7428
 comp.lang.eiffel:727 comp.object:11046
Date: 2004-04-23T12:45:47-04:00
List-Id: <comp.lang.ada>

Georg Bauhaus wrote:
> How would you write "once" routines in C++?

With a static method containing a static value, of course.

class UponATime
{
     static double Once(/* args */)
     {
         static double value = /* some calculation */;
         return value;
     }
};

It appears from my looking up what once functions do,
that arguments to the call are irrelevant for determining
whether it should be re-executed. If so, that's another
example of a hideous language design choice made by Eiffel.

> How about the fine grained visibility control (where each feature
> can be made visible to only a specified set of types)?

Speaking of hideous design decisions. This whole concept
of classes having fine-grained dictatorial control over
whom they allow access to their innards is more than a
little silly.

> They are different I think. Can you express
>  deferred class C [P -> T]
>  feature foo(x: P): P is deferred end
>  end -- C
> in C++?

Sure. You just don't define the method, and if it gets used,
the linker will complain. Or if it's virtual, then you can
make it abstract.

template <typename T>
struct C
{
     T foo(T x);
     virtual T bar(T x) = 0;
};