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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,86ec22e070e319c0
X-Google-Attributes: gid103376,public
From: Simon Wright <simon@pogner.demon.co.uk>
Subject: Re: How do I get this to work??
Date: 1999/01/16
Message-ID: <x7vn23jmwfg.fsf@pogner.demon.co.uk>#1/1
X-Deja-AN: 433296928
X-NNTP-Posting-Host: pogner.demon.co.uk:158.152.70.98
References: <76s0dp$1v4$1@nntp3.uunet.ca> <76tbvv$ba5$1@nntp3.uunet.ca>
 <uiuelbj6r.fsf@gsfc.nasa.gov> <770ifd$qui$1@goblin.uunet.ca>
 <771bl9$sla$1@nnrp1.dejanews.com>
 <BrBl2.6251$Kg6.44094@news2.telusplanet.net>
 <x7vpv8pkjtt.fsf@pogner.demon.co.uk> <77b9cp$5kh$1@nnrp1.dejanews.com>
 <GIVn2.8028$Kg6.59441@news2.telusplanet.net>
X-Complaints-To: abuse@demon.net
X-Trace: news.demon.co.uk 916487117 nnrp-01:8836 NO-IDENT
 pogner.demon.co.uk:158.152.70.98
Organization: At Home
Newsgroups: comp.lang.ada
Date: 1999-01-16T00:00:00+00:00
List-Id: <comp.lang.ada>

warwicks@telusplanet.net (Chris Warwick) writes:

> I will admit some guilt at being a "reformed" C programmer... But, what I find 
> odd is the concept that pointing to an object on the "stack" is poor practice. 
> 
> Even from my Ada83 days, the only "safe" way to do dynamic memory allocation 
> was though the use of local variables on the stack. If I understand this 
> concept, then the view is that it is better to point to a newly allocated 
> buffer, then it is to point to a procedure's local variable. Given that most 
> Ada compilers have no way to deallocate memory, I seem to be trading the 
> potential for a pointer to exist past the life of the allocated memory for a 
> program continously allocates memory...

Most Ada compilers support Ada.Unchecked_Deallocation.
Even Ada83 compilers supported Unchecked_Deallocation.

Pardon me if I'm wrong, but I think what you're missing may perhaps be
the concept of 'in out' (or just 'out') parameters? especially since
you can use unconstrained types.

    procedure Foo is

      type Buffer_Range is range 1 .. 1024;
      type Buffer is array (Buffer_Range range <>) of Integer;

      procedure Process_Buffer (The_Buffer : in out Buffer) is
      begin
        for I in The_Buffer'Range loop
          The_Buffer (I) := Integer (I);    -- etc
        end loop;
      end Process_Buffer;

      B : Buffer (20 .. 47);
      N : Buffer (1 .. 0);                  -- a zero-length instance

    begin

      Process_Buffer (B);
      Process_Buffer (N);

    end Foo;