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,
	T_FILL_THIS_FORM_SHORT autolearn=unavailable autolearn_force=no
	version=3.4.4
X-Received: by 10.107.19.41 with SMTP id b41mr24523378ioj.5.1448274237512;
        Mon, 23 Nov 2015 02:23:57 -0800 (PST)
X-Received: by 10.183.3.106 with SMTP id bv10mr288115obd.17.1448274237483;
 Mon, 23 Nov 2015 02:23:57 -0800 (PST)
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!news.glorb.com!mv3no573775igc.0!news-out.google.com!f6ni10954igq.0!nntp.google.com!mv3no573771igc.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Mon, 23 Nov 2015 02:23:57 -0800 (PST)
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com;
 posting-host=94.107.233.114;
 posting-account=6m7axgkAAADBKh082FfZLdYsJ24CXYi5
NNTP-Posting-Host: 94.107.233.114
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <b4aee46c-7dbb-4906-99c5-f4f8e9876fc6@googlegroups.com>
Subject: operation can be dispatching in only one type
From: Serge Robyns <serge.robyns@gmail.com>
Injection-Date: Mon, 23 Nov 2015 10:23:57 +0000
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Xref: news.eternal-september.org comp.lang.ada:28500
Date: 2015-11-23T02:23:57-08:00
List-Id: <comp.lang.ada>

Guys,

I'm facing an issue with Ada when it comes to use an operation on two tagge=
d types.  It isn't a road blocker and I've found my way around and are not =
using tagged types for these anymore.  I've now a function that computes th=
e total balance every time.  Another option is to pass the id and then sear=
ch the map.

However in C++ it does work as I expected.

Let's say I've the following tagged types.

   type T_Balance is tagged record
      Id       : T_Balance_Id;
      Name     : T_Balance_Name;
      Balance  : T_Amount;
   end record;

   package Balance_Map is new
     Ada.Containers.Ordered_Maps (Key_Type   =3D> T_Balance_Id,
                                  Element_Type =3D> T_Balance);

   type T_Account is tagged record
      Name             : T_Account_Name;
      Total_Balance    : T_Money;
      Balances         : Balance_Map.Map;
   end record;

And I want to have an operation increasing a balance and the total in the a=
ccount.
The following declaration is refused:

   procedure Update_Balance
     (Self   : in out T_Account;
      AB     : in out T_Balance;
      Amount : in     T_Money);

My hope was that it gets dispatched to the right operation on Self which in=
 turns will call the right operation on AB.  But the compiler seems not to =
agree.

in C++:
class account {
public:
	account_id id;
	account_name name;
        money total_balance;
	balance_list balances;

	account();
	virtual ~account();

	void update_balance (account_balance& ab, money amount);
};

void account::update_balance (account_balance& ab, money amount)
{
	ab.update_balance(amount);
	total_balance.amount +=3D amount;
}