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,e9ec140e4d84359f,start
X-Google-Attributes: gid103376,public
From: matomira@di.epfl.ch (Fernando Mato Mira)
Subject: No multiple dispatch in Ada95?
Date: 1995/04/05
Message-ID: <3lu8tp$eep@disunms.epfl.ch>#1/1
X-Deja-AN: 100939354
distribution: world
content-type: text/plain; charset=iso-8859-1
organization: Ecole Polytechnique Federale de Lausanne
mime-version: 1.0
newsgroups: comp.lang.ada
Date: 1995-04-05T00:00:00+00:00
List-Id: <comp.lang.ada>

Hello,

  I checked the reference manual. There's no multiple dispatching
in Ada95?

  I see no reason why a left-to-right disambiguating rule was not good enough.
  You only add the extra dispatching complexity when the methods defined
require it. And it should be faster than simulating it by
a `double dispatch'. What's worse, time is already wasted checking
for a Constraint_Error.

  I have to leave CLOS for a year. I would have exchanged multiple
inheritance for multiple dispatch. Now it's not clear that the effort
or risk of choosing Ada95 instead of C++ (yuck!) is worth it.
  [Yes, I know C++ is risky _by design_]

  Really big goof, and it's a pity given that Ada got the `message send'
  syntax right..


PS: And why not reaping the benefits of both single inheritance
   and contract-based design by restricting inheritance to
   only one parent with structure plus an arbitrary number of abstract
   parents with null records?

-- 
F.D. Mato Mira           http://ligwww.epfl.ch/matomira.html                  
Computer Graphics Lab    matomira@epfl.ch 
EPFL                     FAX: +41 (21) 693-5328