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-Thread: 103376,ace9bff8eb84e5b1
X-Google-Attributes: gid103376,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!postnews.google.com!d21g2000prf.googlegroups.com!not-for-mail
From: Adam Beneschan <adam@irvine.com>
Newsgroups: comp.lang.ada
Subject: Re: Generic Zero Length Array
Date: Fri, 22 Feb 2008 08:52:39 -0800 (PST)
Organization: http://groups.google.com
Message-ID: 
 <4c024f41-3ff8-4d70-ac6c-551f129289a1@d21g2000prf.googlegroups.com>
References: 
 <9b771018-fb0b-42eb-ae00-12ee3eda69b2@p43g2000hsc.googlegroups.com>
	<Pine.LNX.4.64.0802221510150.9614@th.informatik.uni-mannheim.de>
NNTP-Posting-Host: 66.126.103.122
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-Trace: posting.google.com 1203699159 1278 127.0.0.1 (22 Feb 2008 16:52:39
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Fri, 22 Feb 2008 16:52:39 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: d21g2000prf.googlegroups.com; posting-host=66.126.103.122;
	posting-account=duW0ogkAAABjRdnxgLGXDfna0Gc6XqmQ
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.7.12)
	Gecko/20050922 Fedora/1.7.12-1.3.1,gzip(gfe),gzip(gfe)
Xref: g2news1.google.com comp.lang.ada:19978
Date: 2008-02-22T08:52:39-08:00
List-Id: <comp.lang.ada>

On Feb 22, 6:23 am, Stefan Lucks <lu...@th.informatik.uni-mannheim.de>
wrote:
> On Fri, 22 Feb 2008, shaunpatter...@gmail.com wrote:
> > How do I initialize this array when I can't know what type it is or
> > will be?
> > if Error_Condition then
> >  declare
> >    type Result is new Element_List (Indexing.First + 1 ..
> > Indexing'First);
> >    Result_String : Result;
>
>      Result_String : Result := (others => Some_Default_Value);
>
> >  begin
> >     return Element_List (Result);
> >  end;
> > end if;
>
> This should work. The default value doesn't matter at all, because the
> array is empty. But you still need to know a default value of the
> appropriate type.

If the *only* use of this default value would be to use it as an
initializer for an array that we know is going to be empty, so that
the default value is never used, I don't think I'd recommend this
solution.  It may work to get rid of the warnings, but it seems like a
poor design idea to require a parameter that is never used.

I think one of Bob's solutions is preferable, if it's really necessary
to get rid of the warnings.  This is simply a case where you know more
than the compiler.

However, in a case where you do need to initialize something of a
generic formal type, adding an "initial value" generic parameter is
the way to do it.

                                    -- Adam