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List:       kde-core-devel
Subject:    RE: Proposal for dcopidl/dcopidl2cpp improvement
From:       David Faure <David.Faure () cramersystems ! com>
Date:       1999-11-12 13:58:12
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> Hi,
> 
> On Thu, 11 Nov 1999, David Faure wrote:
> 
> > Up to now, one has to create a new class (like the *IFace classes)
> > in order to run dcopidl on it. But since DCOPObject isn't a
> > QObject, why shouldn't one be able to add the DCOPObject implementation
> > to an existing class (which can be a QObject) ?
> > 
> > I've just been trying to run dcopidl on something like :
> > class MyWin : public KTMainWindow, DCOPObject {
> >   K_DCOP
> >   Q_OBJECT
> > public:
> > ... (constructor, destructor, methods, members, everything)
> > k_dcop:
> >  void loadURL( QString url );
> > 
> > 
> > I fixed dcopidl to ignore Q_OBJECT, no problem.
> > The problem is that dcopidl2cpp behaves strangely with multiple
inheritance :
> > - it assumes that all super classes are DCOPObjects 
> >    (it calls the ::process method on <classname>_stub)
> >   Obviously KTMainWindow_stub::process doesn't exist :)
> > - it calls the constructor of the first super class only
> >   (and I can't make DCOPObject the first one since Q_OBJECT has to be
the first one)
> > In fact dcopidl2cpp is able to deal with 1 parent class if it's any
DCOPObject child, but
> > not with 2 parent classes.
> > 
> > The fix I'm thinking of would be simple : ignore parent classes and
always 
> > assume we inherit only from DCOPObject.
> > 
> > [ When I remove manually <SUPER name="KTMainWindow"/> from the .kdil
file, everything
> >   works fine ]
> > 
> > Obviously it wouldn't be possible to inherit a dcopidl interface from
another.
> > Is this a problem for anybody ? (The current code doesn't do that at
all, but in
> > the future, I don't know).
> > 
> > AFAICS, we can't have both. Because dcopidl2cpp has no way to know which
> > parent classes are DCOPObjects and which aren't. Or we need to introduce
yet
> > another tag for that, to tell dcopidl2cpp what to do.
> 
> I dont like to drop inheritance. It was for long times a bad constraint
> on Visual Basic for example.
> 
> But your problem can be fixed in another way:
> Always assume that the right most super class is the DCOPObject or
> DCOPObject derived one. That works in cases with no multiple
> inheritance and always works if you inherit from some QObject class,
> since the QObject class has always to be leftmost.
Yes, I thought about that.
It means you can't multiple-inherit from two DCOPObject-derived classes,
but that would be a limitation we can accept :)
Just like you can't derive from two QObjects at the same time.

> Simple fix and your problem should be solved, or did I overlook
> something ?
That should fix it.
I'll modify dcopidl2cpp for this.

Thanks.

--
David Faure
faure@kde.org - KDE developer
david@mandrakesoft.com - Mandrake
david.faure@cramersystems.com - Cramer Systems

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