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=-0.9 required=5.0 tests=BAYES_00,FORGED_GMAIL_RCVD,
	FREEMAIL_FROM autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,1e36228aae0595da,start
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,UTF8
Path: 
 g2news1.google.com!news2.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!news.k-dsl.de!news.motzarella.org!motzarella.org!not-for-mail
From: =?UTF-8?B?UGF3ZcWCICdOaXZlcnRpdXMnIFDFgmF6aWXFhHNraQ==?=
 <nivertius@gmail.com>
Newsgroups: comp.lang.ada
Subject: Access to function returning class-wide type
Date: Thu, 21 Aug 2008 12:13:10 +0200
Organization: A noiseless patient Spider
Message-ID: <g8jf3n$e00$1@registered.motzarella.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8Bit
X-Trace: feeder.motzarella.org
 U2FsdGVkX19NAfMqbEtBcRMxtS7QsmQNmZwbQTGC8F56k2eYQgMwxKMR6cJjRHSgaJ2jBItzvv+dKnAkTM0tpH6zr+N1QIXf0dxVFrnBAu7JtTs7bhjssv0ZCrEoszRu7G9YHK2+jbkzKktH1fjrHQ==
X-Complaints-To: Please send complaints to abuse@motzarella.org with full
 headers
NNTP-Posting-Date: Thu, 21 Aug 2008 10:13:11 +0000 (UTC)
X-Auth-Sender: U2FsdGVkX1/Ed+kZZhOd9ULod+o0rxU4zfScAyrZSlTDi2p6fShP3w==
Cancel-Lock: sha1:2dn2Y6sCCiwJRYWS5cYVZBl525s=
User-Agent: KNode/0.10.9
Xref: g2news1.google.com comp.lang.ada:1718
Date: 2008-08-21T12:13:10+02:00
List-Id: <comp.lang.ada>

Hello all.

I'm new here, but I'll try to stick on.

Let me start with a tricky problem:

Consider following code:

----------------------------------------

package A is 
        type Abstracted is abstract tagged null record;
        function Proc (N : Natural) return Abstracted is abstract;

        type The_Access_Type is access function (N : Natural) return
Abstracted'Class;

end A;

-- package A body ommited;

with A;
package B is 
        type Derived is new A.Abstracted with null record;
        function Proc (N : Natural) return Derived;

        Failing_Object : A.The_Access_Type := B.Proc'Access;
        --  will not compile, error: 'expected type The_Access_Type / found type
access function Proc defined at ...'

        function Proc_Wrapper (N : Natural) return Abstracted'Class;

        Working_Object : A.The_Access_Type := B.Proc_Wrapper'Access;
        -- compiler doesn't complain

end B;

package B body is
        function Proc_Wrapper (N : Natural) return Abstracted'Class is
        begin
                return Abstracted'Class'(Proc (N));
        end Proc;

        -- function Proc body ommited
end B;

----------------------------------------

What I need is a access type to 'constructor' of an derivate of abstract
object.
As I presented, there is a workaround, but that's not the 'right' way to do
it. I really want to do it without some tricky wrapping.
How do I define The_Access_Type to do what I want?

Thanks in advance.

-- 
Paweł Płazieński aka Nivertius
"In the end, there will be Ada, XML and gzip"