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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,a5d76152c5cb8790
X-Google-Attributes: gid103376,public
From: Stephen Leake <Stephen.Leake@gsfc.nasa.gov>
Subject: Re: class-wide objects
Date: 1998/12/11
Message-ID: <u1zm6bc9j.fsf@gsfc.nasa.gov>#1/1
X-Deja-AN: 421320563
References: <366B1190.C8142307@magic.fr> <m3emqc689e.fsf@mheaney.ni.net>
 <366EE6BA.7D586BDD@magic.fr> <m31zm84g2m.fsf@mheaney.ni.net>
Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA
Newsgroups: comp.lang.ada
Date: 1998-12-11T00:00:00+00:00
List-Id: <comp.lang.ada>

Matthew Heaney <matthew_heaney@acm.org> writes:

> Then just make it non-primitive:
> 
> generic
>    ...
> package Stacks is
> 
>    type Stack_Type is ...
> ...
>    package Constructors is
> 
>       function  Copy (Stack : Stack_Type) return Stack_Access;
> 
>    end;
> ...
> end Stacks;
> 
> 
> Because Copy is non-primitive, it won't get inherited during derivation.
> 

Another way to make an operation non-primitive is to use 'class:

function Copy (Stack : Stack_Type'class) return Stack_Access;

I've been flip-flopping about which way is "best". Using 'class
sometimes implies re-dispatching in the body, but not always. If the
non-primitive operations belong in a group (like Constructors), then
the local package seems neat. But for other operations, a local
package is just noise, and 'class seems preferable.

-- Stephe