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List:       kde-core-devel
Subject:    Re: QUrl in KDE 4
From:       Frans Englich <frans.englich () telia ! com>
Date:       2005-05-20 14:55:03
Message-ID: 200505201455.03808.frans.englich () telia ! com
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On Friday 20 May 2005 08:17, christian.loose@hamburg.de wrote:
> -----Ursprüngliche Nachricht-----
> Von: jfirebaugh@kde.org
> Gesendet: Freitag, 20. Mai 2005 05:08
> An: kde-core-devel@kde.org
> Betreff: Re: QUrl in KDE 4
>
> > On May 19, 2005, at 7:02 PM, Frans Englich wrote:
> > > As Thiago, I disagree, because with that approach you will find the
> > > problem in
> > > any object oriented design; where something is a subset,
> > > constrainment, of
> > > something wider -- what class hierarchies usually are about,
> > > AFAICT. A square
> > > is a subset of the recangle's value space, so to speak.
> >
> > [snip]
> >
> > > Hence, I don't see representation problem Thiago sees. Perhaps an
> > > elaboration
> > > can be provided?
> >
> > On the contrary, class hierarchies are ill suited to this type of
> > subset relationship:
>
> [snip]
>
> > Inheriting the other way around doesn't work either.
> >
> > See also http://c2.com/cgi/wiki?CircleAndEllipseProblem
> >
> > The URL/URI relationship is very similar.
>
> One can find another good explanation for this problem in the C++ FAQ Lite.
> See [21.6] till [21.12]:
> http://www.parashift.com/c++-faq-lite/proper-inheritance.html#faq-21.6


John, Christian,

Thanks for the links.


		Frans

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