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=ham autolearn_force=no version=3.4.4
X-Google-Thread: 103376,910a48a538936849
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!news.buerger.net!open-news-network.org!news.teledata-fn.de!newsfeed.arcor.de!newsspool3.arcor-online.net!news.arcor.de.POSTED!not-for-mail
Newsgroups: comp.lang.ada
Subject: Re: how to import a package
From: Georg Bauhaus <bauhaus@arcor.de>
In-Reply-To: <1165893584.829025.235440@l12g2000cwl.googlegroups.com>
References: <1165371252.358817.57840@80g2000cwy.googlegroups.com>
	 <sa4veko5ndy.fsf@margay.local> <4577dc92$1_1@glkas0286.greenlnk.net>
	 <7ft8le.vk1.ln@hunter.axlog.fr>
	 <1165817760.736164.218530@73g2000cwn.googlegroups.com>
	 <1165819804.449958.305980@73g2000cwn.googlegroups.com>
	 <1165830005.15844.5.camel@localhost>
	 <1165846777.475130.199390@f1g2000cwa.googlegroups.com>
	 <Abjfh.1093829$084.864157@attbi_s22>
	 <1165893584.829025.235440@l12g2000cwl.googlegroups.com>
Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Organization: #
Message-ID: <1165920993.21859.15.camel@localhost>
Mime-Version: 1.0
X-Mailer: Evolution 2.6.1 
Date: Tue, 12 Dec 2006 11:56:34 +0100
NNTP-Posting-Date: 12 Dec 2006 11:55:44 CET
NNTP-Posting-Host: 1cd48dbf.newsspool4.arcor-online.net
X-Trace: 
 DXC=EVk\gc7RI`:=FQB?mjjV504IUK<Cl32<14Fo<]lROoR14nDHegD_]R5b?QQ5IGn]I?N[W<lHX`=B4\6BhD5G6\i<Yf0=T09aC99
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news2.google.com comp.lang.ada:7900
Date: 2006-12-12T11:55:44+01:00
List-Id: <comp.lang.ada>

On Mon, 2006-12-11 at 19:19 -0800, markww wrote:


> I'm wondering still if it's possible to have a data member in the
> package definition that serve as my start and end nodes.

As Jeffrey and Stuart have explained, you are still led astray
by a misconception: A C++ struct/class here corresponds to an Ada
type, not to an Ada package. Although you need a package to
associate the "methods" with the tagged type, all data members
must become the record components in the type definition.

C++: From a struct or class, you create objects.
Ada: From a type, you create objects.

C++: Operations of a type are declared within the struct/class
Ada: Operations of a type are declared after the type within
     a surrounding package.

Compare the following definitions:

namespace Geo
{
  struct Any
  {
    int x, y;
    virtual void move(int a, int b) = 0;
  };

  struct Point : public Any
  {
    virtual void move(int a, int b);
  };

  struct Circle : public Any
  {
    int r;
    virtual void move(int a, int b);
  };
}


package Geo is

   type Any is abstract tagged record
      x, y: Integer;
      -- data members of any geometric object
   end record;

   procedure move(thing: in out Any; a, b: Integer) is abstract;
   -- abstract method of Any



   type Point is new Any with record
      null;
         -- no additional data members
   end record;

   --overriding
   procedure move(thing: in out Point; a, b: Integer);



   type Circle is new Any with record
      r: Integer;
      -- Circle objects with radius
   end record;

   --overriding
   procedure move(thing: in out Circle; a, b: Integer);

end Geo;

HTH,
-- Georg