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From: matomira@di.epfl.ch (Fernando Mato Mira)
Subject: Re: No multiple dispatch in Ada95?
Date: 1995/04/07
Message-ID: <3m3c72$5ms@disunms.epfl.ch>#1/1
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references: <3lu8tp$eep@disunms.epfl.ch> <1995Apr6.163750.11289@wdl.loral.com>
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organization: Ecole Polytechnique Federale de Lausanne
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Date: 1995-04-07T00:00:00+00:00
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In article <1995Apr6.163750.11289@wdl.loral.com>, mab@dst17.wdl.loral.com (Mark A Biggar) writes:

> useless.  Note that the only dispatching operations in Ada95 are 
> the primitive operation of the tagged type and those can only be
> defined in the same package spec as the tagged type declaration itself
> and even then only until you do something to freeze the type (like
> derive another type from it). 

I was also dissapointed by this. I found that the inability of
defining a new virtual for a set of classes without access to
source code is a slap in the face to reuse (of couse, such new operations
should live in a different package, to avoid problems when you get
a new release of that library).


> That solves the duplicate data member problem but doesn't solve the duplicate
> operation problem.

I know. I was not looking at name clash problems. Eiffel does just fine,
and its solutions to the latter are less of an efficiency concern
as the support for multiple inheritance of data members.

BTW, hierarchical packages are cool. I argued about this some time
ago in comp.lang.lisp, and I was happy to see them in Ada95

Given the quest of both lispers and ada fans for _The_Right_Thing_
(with a different set of values), the support for multiple dispatching
in both would have made a nice parallel and a good delivery
option when MOP or dynamic features were not required.
And given that the DoD puts money in Lisp projects, too, that might
have looked interesting to them.. Oh, well..*sigh*

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