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-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,9f3d09bde7b33b5d
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2004-04-09 05:57:12 PST
Path: archiver1.google.com!postnews1.google.com!not-for-mail
From: dan.r.mcleran@seagate.com (Dan McLeran)
Newsgroups: comp.lang.ada
Subject: Re: Pass by reference
Date: 9 Apr 2004 05:57:11 -0700
Organization: http://groups.google.com
Message-ID: <19b0e504.0404090457.52013e4@posting.google.com>
References: <19b0e504.0404080652.4eab9f80@posting.google.com>
 <pOmdc.1712$k05.963@newsread2.news.pas.earthlink.net>
NNTP-Posting-Host: 192.55.20.36
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: posting.google.com 1081515431 8306 127.0.0.1 (9 Apr 2004 12:57:11
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Fri, 9 Apr 2004 12:57:11 +0000 (UTC)
Xref: archiver1.google.com comp.lang.ada:6901
Date: 2004-04-09T05:57:11-07:00
List-Id: <comp.lang.ada>

> The Ada rules, simple version, for parameter passing mechanisms, are:
> 
> Elementary types are always passed by copy.
> 
> Tagged and private types are always passed by reference.
> 
> Other types have the mechanism chosen by the compiler.

That's what I thought. The RM is actually very clear about this, but
it seems that alot of people assume compilers have more leeway. Alot
of the answers indicate that people think the compiler is always free
to choose the best convention. I don't believe this is true. A
conforming compiler should do exactly what the RM says, which is what
your short-version says.

> The parameter mode (in, in out, and out) is completely unrelated to the 
> parameter passing mechanism.
> 
> Generally, compilers do a good job of choosing the mechanism for "other 
> types". It might be informative to check the mechanism used for
> 
> type T is array (1 .. Integer'Size) of Boolean;
> pragma Pack (T);

I'll check it out, Thanks.