Re: Sugestion to Multiple Inheritance

[Ole-Hjalmar Kristensen <oleh@vlinux.voxelvision.no>]

John English <je@brighton.ac.uk> writes:

> Hyman Rosen wrote:
> > 
> > Richard Riehle wrote:
> >  > Multiple inheritance is just one feature
> > 
> > > I find, if not a disaster, at least, as you say, overly-complicated,
> > > and inconvenient.
> > 
> > Actually, the complications are in the compiler, because of technical
> > aspects of how objects must behave during their construction. In use,
> > MI works for C++ users pretty much exactly as they expect.
> 
> Unless you have a diamond-shaped hierarchy:
>               A
>              / \
>             B   C
>              \ /
>               D
> in which case you get into the nasty world of virtual base classes
> and the assorted surprises that they bring with them. Anyone who
> finds that MI works "pretty much exactly as they expect" in this
> situation has a better imagination than average, IMHO.

I have lots of diamond-shaped hierarchies in my code to implement mixins.
It *USUALLY* works as expected by me. Other readers of the code tend to be 
confused. It is a nice idiom, but can be very confusing for people who have
not seen it before.


> 
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>  John English              | mailto:je@brighton.ac.uk
>  Senior Lecturer           | http://www.it.bton.ac.uk/staff/je
>  Dept. of Computing        | ** NON-PROFIT CD FOR CS STUDENTS **
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