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From: Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: Abstract Functions
Date: 16 Jul 2001 17:51:32 -0400
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"Marin David Condic" <marin.condic.auntie.spam@pacemicro.com> writes:

> That is one possible way to go. However, what I have is a working parent
> type that does useful things in its own right. It would be useful to have a
> way of keeping it executable, but adding one or more operations that would
> require extension. 

What does that mean? How can it be both "executable" (presumably
without declaring a derived type), and "require extension" (presumably
by requiring a derived type). This seems inherently contradictory,
which may be why you are having trouble doing it :).

> Basically, if you have a type that is a few generations down the
> inheritance tree and now want to add some abstract operations, the
> only way to do that is make the whole tree of types abstract. I'd
> prefer not to do that.

Ok, make it generic.

> Its the sort of thing where I've gone down a chain of inheritance
> and said "O.K. Now I need the user to provide me with some functions
> and I don't want to make this generic." 

Ok, use pointers to functions.

> I suppose I could use pointers to functions but I've never liked
> that answer.

Ok, we've suggested all the Ada ways, and you've said "I don't wanna".
Go use C++ :).

Seriously, you need to give more detailed reasons why all these ideas
are bad.

-- 
-- Stephe