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,FREEMAIL_FROM,
	INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII
X-Google-Thread: 103376,3b7d2943d4e48cd3
X-Google-Attributes: gid103376,public
From: Damien Carbonne <damien.carbonne@free.fr>
Subject: Re: generic formal primitive [dispatching] operation
Date: 2000/09/19
Message-ID: <39C92E15.5EA5FACE@free.fr>#1/1
X-Deja-AN: 671785012
Content-Transfer-Encoding: 8bit
References: <39C5321E.805A73D1@free.fr> <wccog1ln229.fsf@world.std.com>
X-Accept-Language: en
Content-Type: text/plain; charset=iso-8859-1
X-Complaints-To: abuse@proxad.net
X-Trace: nnrp5.proxad.net 969399132 212.27.44.165 (Tue,
 19 Sep 2000 23:32:12 CEST)
Organization: Guest of ProXad - France
MIME-Version: 1.0
NNTP-Posting-Date: Tue, 19 Sep 2000 23:32:12 CEST
Newsgroups: comp.lang.ada
Date: 2000-09-19T00:00:00+00:00
List-Id: <comp.lang.ada>

Robert A Duff a �crit :

> Damien Carbonne <damien.carbonne@free.fr> writes:
>
> > I would like to create a generic package that has, as formal parameters,
> > a tagged type and some primitive dispatching operations on that type.
>
> Try using a generic formal derived type.  Declare the root type outside
> the generic, with the primitive you want, and then declare a generic
> formal type derived from that.
>

As I explained in my answer to Thomas Quinot, I would like to avoid this
solution, because it is a bit more rigid than what
I expect. But if what I expect is impossible, I will come back to it.

>
> > 1) How is it possible to define a formal primitive operation on a tagged
> > type that is:
> >    a) non dispatching (Root'Class ??)
>
> Primitive = dispatching (for tagged types).  Class-wide types are not
> primitive.
>
> >    b) dispatching
>
> See above.
>
> > 2) In the case of class-wide operations, is there any difference between
> > primitive and non primitive
> >    operations ? (I would say no ?)
>
> A class-wide operation is *not* primitive.
>
> - Bob

Sorry, I thought "primitivity" was only related to declarative region
+ freezing rules.
But it is in fact more restricted.

Is the following example correctly labelled ?
package P is
   type T is tagged null record;
   procedure Primitive(Obj : T);
   procedure Class_Wide(Obj : T'Class);
end P;

with P; use P;
package O is
   procedure What_Is_Its_Category(Obj : T);
   procedure Again_Class_Wide(Obj ; T'Class);
end O;


Can we consider that in the following declarations:
generic
   type Root is tagged private;
   with procedure P1(This : access Root);
   with procedure P2(This : access Root'Class);


1) P1 is primitive (that is dispatching). Root can be derived and P1
redefined. (It seems to be the case in
   the example I put in my answer to T.Quinot)
2) P2 is class-wide.

If this is true, my problem is, how is it possible to make the initial
example work, keeping the same spec (just changing the body).

Thanks for clarifications.

Damien.