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
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Private extension of a synchronized interface
Date: Mon, 18 Feb 2019 08:33:37 +0000
Organization: A noiseless patient Spider
Message-ID: <lyd0npo5r2.fsf@pushface.org>
References: <fd975d66-8e70-4e86-8a75-efc6061ef25c@googlegroups.com>
	<lypnrqnitl.fsf@pushface.org>
	<bc3cde96-2655-4cd7-9b69-aecba3963f71@googlegroups.com>
Mime-Version: 1.0
Content-Type: multipart/mixed; boundary="=-=-="
Injection-Info: reader02.eternal-september.org;
 posting-host="be5f75c042c6e7a51c0c430d9866770f";
	logging-data="3272"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX19CWgJxXBp498osuvKj2T2vFBZpdlORVqQ="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (darwin)
Cancel-Lock: sha1:Whtlfrw3WVFwabaGi66agGzskMc=
	sha1:pUmhOh4JJ4lqUHmY+09sq/1gtCY=
Xref: reader01.eternal-september.org comp.lang.ada:55561
Date: 2019-02-18T08:33:37+00:00
List-Id: <comp.lang.ada>

--=-=-=
Content-Type: text/plain

Jere <jhb.chat@gmail.com> writes:

> In the other part that I commented out I was trying to add a publically
> available override to the interface operation, but haven't been successful.
> Do you know of any syntax changes I might need to do to:
>
>         -- The following lines give the errors:
>         -- "p1" conflicts with declaration at line xxx
>         -- and
>         -- missing body for "p1"
>        
>         --overriding
>         --procedure p1(Self : in out Instance); 
>
> So I don't need to always dispatch?

I'm not 100% sure why this works & the other doesn't - I think because
Instantiation.P1 is actually publicly visible.

Also not sure whether you could do away with the inner Instantiation.

Anyway,


--=-=-=
Content-Type: text/plain
Content-Disposition: inline; filename=jere.adb
Content-Description: working example

with Ada.Text_IO; use Ada.Text_IO;

procedure Hello is

   package Example is

      type An_Interface is synchronized interface;
      procedure P1 (Self : in out An_Interface) is abstract;

      package Instantiation is

         type Instance is synchronized new An_Interface with private;

         overriding
         procedure P1 (Self : in out Instance);

      private

         protected type Instance is new An_Interface with
            procedure Actual_P1;
         private
         end Instance;

      end Instantiation;

   end Example;

   package body Example is

      package body Instantiation is

         protected body Instance is
            procedure Actual_P1 is
            begin
               Put_Line("Did Something");
            end Actual_P1;
         end Instance;

         procedure P1 (Self : in out Instance) is
         begin
            Self.Actual_P1;
         end P1;

      end Instantiation;

   end Example;

   V : Example.Instantiation.Instance;

begin
   Put_Line("Hello, world!");

   --  dispatching ...
   Example.An_Interface'Class (V).P1;

   --  not dispatching
   V.P1;
end Hello;

--=-=-=--