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: 103376,5b3aa4bc9027f04e
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news1.google.com!postnews.google.com!v23g2000pro.googlegroups.com!not-for-mail
From: belteshazzar <gbelteshazzar@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Unconstrained Arrays
Date: Mon, 16 Mar 2009 19:58:28 -0700 (PDT)
Organization: http://groups.google.com
Message-ID: 
 <0caa9cf8-0620-4544-9b2c-2c9f24142b7f@v23g2000pro.googlegroups.com>
References: 
 <1a8008fb-c840-45bc-824c-d10eec9fe569@d36g2000prf.googlegroups.com>
	<jkDvl.615065$yE1.211920@attbi_s21>
NNTP-Posting-Host: 203.36.107.146
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1237258708 23906 127.0.0.1 (17 Mar 2009 02:58:28
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Tue, 17 Mar 2009 02:58:28 +0000 (UTC)
Complaints-To: groups-abuse@google.com
Injection-Info: v23g2000pro.googlegroups.com; posting-host=203.36.107.146;
	posting-account=SuaatgoAAADZMrKGiLdPOjCBBS4KZzVT
User-Agent: G2/1.0
X-HTTP-Via: 1.1 SRV021
X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR
	2.0.50727; .NET CLR 3.0.04506.30),gzip(gfe),gzip(gfe)
Xref: g2news1.google.com comp.lang.ada:4152
Date: 2009-03-16T19:58:28-07:00
List-Id: <comp.lang.ada>

On Mar 17, 11:49=A0am, "Jeffrey R. Carter"
<spam.jrcarter....@spam.acm.org> wrote:
> belteshazzar wrote:
> > I have a program that uses a lot of different sized arrays and passed
> > into math functions. So I'm using an unconstrained array type. The
> > problem that I have is that I'm not allowed to use "new" this means
> > that I have to use pools (which I can't because to intantiate a pool I
> > have to constrain the array type) or allocated the arrays on the
> > stack. Allocating the arrays on the stack is fine, BUT it means that i
> > have to use array initializers so that they remain unconstrained
> > rather than becoming an anonomous contrained type that can no longer
> > be passed to my math functions.
>
> I'm not clear what you're talking about. You can pass a constrained subty=
pe to a
> subprogram that takes a parameter of an unconstrained array type.
>
> For example, String is an unconstrained array type. If we have
>
> function F (S : in String) return Natural;
>
> V : String (1 .. 10);
> C : Natural;
>
> then it's perfectly legal to call F with V as its actual parameter:
>
> C :=3D F (S);
>
> > Also, and the main point of my post, I've found that I can place the
> > unconstrained array inside a record with a distriminant and this seems
> > to solve all our problems. We don't have to use array initialisers and
> > we can get pointers to aliased objects that can be easily passed to
> > the math functions.
>
> Here is your problem. There should be no reason to pass explicit pointers=
 to
> these functions. Your best solution is to rewrite or change your library.
>
> --
> Jeff Carter
> "Drown in a vat of whiskey. Death, where is thy sting?"
> Never Give a Sucker an Even Break
> 106

As we have very large array's we're using something like:


type Unconstrained_Array is array ( Integer range <> ) of Integer;
type Unconstrained_Array_Pointer is access all Unconstrained_Array;

procedure F (S : in Unconstrained_Array_Pointer);

V : Unconstrained_Array :=3D (1 .. 10_000 =3D> 0);
V_Ptr : Unconstrained_Array_Ptr :=3D
Unconstrained_Array'unchecked_Access

F (V_Ptr);


Note the use of the array intialiaser, if this isn't used then the
pointer is no longer compatible.