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From: donh@syd.csa.com.au (Don Harrison)
Subject: Re: Eiffel and Java
Date: 1996/11/12
Message-ID: <E0qMJC.EJt@syd.csa.com.au>#1/1
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organization: CSC Australia, Sydney
reply-to: donh@syd.csa.com.au
newsgroups: comp.lang.eiffel,comp.lang.ada
Date: 1996-11-12T00:00:00+00:00
List-Id: <comp.lang.ada>


Marcos F. F. de Macedo writes:

:Jon S Anthony wrote:
:
:> Right.  As was pointed out back in that old thread, to get at the
:> "separate" spec/impl aspects in Eiffel you would use an "abstract
:> class" technique.  This doesn't quite work, but it is at least the
:> proper analogue.

Jon, don't know why you say this. I have some vague recollection of you
talking about Sather's separate interface and implementation *inheritance*.
But Ada doesn't even support that, so I'm not sure what you're thinking
of. Please explain why you make this association.

:The spec/impl is to separate the way that clients see the class
:(interface) from actual code/structure. This is done in Eiffel by the
:short tool. The short tool generates the interface to an eiffel class
:with more spec. than is done in Ada.
:
:There is no need to write the interface if it could be stracted from the
:source code. I should know that Ada was based on Modula-2 that used this
:way of separating. Oberon, the sucessor of Modula-2, uses automatic
:interface generating tool.

I'm with you on this. Your point was raised in the "Real OO" thread Jon 
refers to. 

This is how I would 'match' these facilities in Ada and Eiffel:

Ada                                   Eiffel
---                                   ------
abstract tagged type                  deferred class
abstract operation                    deferred routine

package interface                     (output of short tool)
package body                          class


Don.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Don Harrison             donh@syd.csa.com.au