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,FREEMAIL_FROM
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!feeder.erje.net!eu.feeder.erje.net!weretis.net!feeder4.news.weretis.net!rt.uk.eu.org!aioe.org!.POSTED!not-for-mail
From: Victor Porton <porton@narod.ru>
Newsgroups: comp.lang.ada
Subject: A good program that not compile
Date: Wed, 21 May 2014 16:05:10 +0300
Organization: Aioe.org NNTP Server
Message-ID: <lli8a9$9g5$1@speranza.aioe.org>
NNTP-Posting-Host: LRua1LhEwYx/r1KnMXeYtA.user.speranza.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7Bit
X-Complaints-To: abuse@aioe.org
User-Agent: KNode/4.12.4
X-Notice: Filtered by postfilter v. 0.8.2
Xref: news.eternal-september.org comp.lang.ada:19947
Date: 2014-05-21T16:05:10+03:00
List-Id: <comp.lang.ada>

The following does not compile.

Nevertheless it is a logical code and it or it variant should be compilable
in a good programming language. I humbly ask: may we make it compilable in
the next version of Ada?

-- my.ads
with Ada.Finalization;

package My is

   type Abstract_Handle is new Ada.Finalization.Limited_Controlled with
      record
         Handle: Integer;
      end record;

   function Obtain_Handle(Object: Abstract_Handle) return Integer is abstract;

   overriding procedure Initialize(Object: in out Abstract_Handle);

   type File_Handle is new Abstract_Handle with null record;

   overriding procedure Obtain_Handle(Object: in out File_Handle);

end My;

-- my.adb
package body My is

   overriding procedure Initialize(Object: in out Abstract_Handle) is
   begin
      Object.Handle := Obtain_Handle(Object);
   end;

   overriding function Obtain_Handle(Object: in out File_Handle) return Integer is
   begin
      return 123; -- Suppose 123 is a file handle, for an example
   end;

end My;


-- 
Victor Porton - http://portonvictor.org