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From: "(see below)" <yaldnif.w@blueyonder.co.uk>
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Subject: Re: Preventing type extensions
Date: Tue, 21 Sep 2010 15:50:56 +0100
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On 21/09/2010 14:57, in article
c75a88c5-1d51-4342-904a-743e41adeb7f@k9g2000vbo.googlegroups.com, "Cyrille"
<comar@eu.adacore.com> wrote:

> On Sep 13, 11:13�pm, "J-P. Rosen" <ro...@adalog.fr> wrote:
> 
>> These arguments make sense for languages without the notion of
>> class-wide types.
> 
> all OO languages I'm aware of, have the notion of classwide types...
> They just don't make the distinction between a type on its own and a
> type with its derived types. If you think about it, it is a peculiar
> distinction at the "design" level. A horse is an animal... When I deal
> with animals, I must be ready to accept that maybe the animal I'm
> dealing with may be a horse, or may be something else. It's peculiar
> to expect it to be the pure notion of "animal" and nothing else...

What is peculiar about abstraction?

-- 
Bill Findlay
<surname><forename> chez blueyonder.co.uk