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=-0.9 required=5.0 tests=BAYES_00,FORGED_GMAIL_RCVD,
	FREEMAIL_FROM autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,901cf02e3fdf0c96
X-Google-Attributes: gid103376,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!postnews.google.com!o11g2000prd.googlegroups.com!not-for-mail
From: kevin  cline <kevin.cline@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: SI Units - has Ada missed the boat?
Date: Wed, 18 Jul 2007 00:11:12 -0700
Organization: http://groups.google.com
Message-ID: <1184742672.910297.54010@o11g2000prd.googlegroups.com>
References: <1183907619.564482.240470@w3g2000hsg.googlegroups.com>
NNTP-Posting-Host: 76.186.29.123
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
X-Trace: posting.google.com 1184742673 7963 127.0.0.1 (18 Jul 2007 07:11:13
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Wed, 18 Jul 2007 07:11:13 +0000 (UTC)
In-Reply-To: <1183907619.564482.240470@w3g2000hsg.googlegroups.com>
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US;
 rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4,gzip(gfe),gzip(gfe)
Complaints-To: groups-abuse@google.com
Injection-Info: o11g2000prd.googlegroups.com; posting-host=76.186.29.123;
   posting-account=ps2QrAMAAAA6_jCuRt2JEIpn5Otqf_w0
Xref: g2news1.google.com comp.lang.ada:16505
Date: 2007-07-18T00:11:12-07:00
List-Id: <comp.lang.ada>

On Jul 8, 10:13 am, Martin <martin.do...@btopenworld.com> wrote:
> One of my pet hopes for Ada2005 was that it would include some method
> of automatically checking systems of units at compilation time or with
> minimal run-time checking. Alas it was voted down due to time
> pressures and technical issues (seehttp://www.ada-auth.org/ai-files/minutes/min-0403.html#AI324
> andhttp://www.ada-auth.org/cgi-bin/cvsweb.cgi/AIs/AI-00324.TXT?rev=1.3).
>
> C++ now has the Boost library (seehttp://svn.boost.org/trac/boost/browser/sandbox/units)
> with zero-runtime cost (or at least when optimisation is switched on).

A basic but usable implementation is obvious to anyone who understands
C++ template metaprogramming.  Of course a fully general
implementation is considerably more work.

>
> And now Java has a proposal for a similar beast (seehttps://jsr-275.dev.java.net/files/documents/4333/34956/jsr-275.pdf).

This is rather unwieldy since Java does not allow operator
overloading.  Who wants to read code like:

   time_aloft = sqrt(height.times(2).divide(g))

Nor can Java check the correctness of that computation at compile
time.

>
> I've been playing around with the C++ Boost library and it seems quite
> good - at least for the sort of things I would use it for (embedded
> avionics).


>
> Is anyone still working on an Ada solution to this?

A satisfactory solution seems impossible until Ada allows implicit
generic instantiation, and then it would be relatively simple.