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From: Graham Hughes <graham.hughes@resnet.ucsb.edu>
Subject: Ada OO
Date: 1996/11/25
Message-ID: <57aq7s$30j@yuggoth.ucsb.edu>#1/1
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organization: University of California, Santa Barbara
newsgroups: comp.lang.ada
Date: 1996-11-25T00:00:00+00:00
List-Id: <comp.lang.ada>


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I apologize if this has been glossed over before, but I didn't notice
anything immediately through the back articles.

The tutorials at http://www.adahome.org/ seem to gloss over the way Ada
OO is handled; possibly this is because they believe it to be so simple
that their explanation suffices.  However, I'm coming from C++, where OO
is quite complicated, and I'm not sure I've quite got a handle on it
yet.

- From what I've seen, Ada OO is very similar to CLOS; both use the

    Object_Method(Object, Args);

syntax instead of the C++-style

    Object.Object_Method(Args);

where Object is a tagged record.

Given this, how are C++-style virtual methods defined?  The stuff I've
looked at implied that all subprograms defined in the package spec are
virtual, and pure virtual methods are achieved by (appending?
prepending?) abstract to the definition.

With CLOS, all defmethod (or is it defgeneric? been a while) methods are
effectively virtual, and pure virtual methods are just a defgeneric (?)
with no body definitions.  Is this the way Ada OO works?

Finally, re: the abstract; is it needed in the package body, or can it
be ommitted?

Thanks for any help.
- -- 
    Graham Hughes (graham.hughes@resnet.ucsb.edu)
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