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: 103376,74b55538385b7366
X-Google-Attributes: gid103376,public
From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Which is right here - GNAT or OA ?
Date: 1999/06/03
Message-ID: <m3wvxll104.fsf@mheaney.ni.net>#1/1
X-Deja-AN: 485303629
References: <928083159.436.79@news.remarQ.com>
NNTP-Posting-Date: Thu, 03 Jun 1999 09:03:28 PDT
Newsgroups: comp.lang.ada
Date: 1999-06-03T00:00:00+00:00
List-Id: <comp.lang.ada>

"Vladimir Olensky" <vladimir_olensky@yahoo.com> writes:

> ----------------------------------
> --  Which is right here - GNAT or OA ?
> ---------------------------------

Both are, because the language doesn't specify what happens when you
try to deallocate an object on the stack.  Your code is erroneous.

 
> I mentioned about my simple user GB examples few months ago in GB
> thread but then I had no time to prepare them for open use.  Then
> there was nice article about smart pointers by Mathew Heaney
> describing the same issue and I did not feel like adding anything else
> to this subject.

My philosophy is to declare the type in such a way so that the user has
to use the type's allocator, and can't declare the object on the stack:

  type T (<>) is limited private;
 
  type T_Access is access all T;


  function New_T return T_Access;

  procedure Free (O : in out T_Access);

  procedure Op1 (O : access T);


Using this technique, the problem you describe cannot happen.