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From: Maarten Kronenburg (M.Kronenburg_at_[hidden])
Date: 2006-05-31 17:32:44

Templates provide compile-time
polymorphism, while derivation provides
run-time polymorphism.
For using mixed expressions with
different types, run-time polymorphism
is required.
Regards, Maarten.

"Stefan Slapeta" <stefan_at_[hidden]> wrote in message
> Maarten Kronenburg wrote:
> >
> > For an abstract base class, derivation is mandatory.
> > This is not what I want, because I want non-demanding
> > users to be able to use the class integer without derivation.
> > On the other hand I also want demanding users to be able
> > to use derivation for defining integers with specific properties
> > such as an unsigned_integer or a modular_integer,
> > and use mixed expressions.
> > When I make the class concrete then users will never
> > be able to derive from it, unless they make a new class
> > with an integer data member and start all over again.
> > I have thought this through, and I think the way it is,
> > it serves both non-demanding and demanding users
> > best with flexibility if needed.
> >
> Sorry, but 'configuration by inheritance' is by far the worst OO design
> 'idea' that has ever been invented by human being. It inhibits reuse
> instead of encouraging it and it's responsible for most of the problems
> in large OO systems I've seen so far. Furthermore, it's a completely
> wrong interpretation of inheritance.
> C++ provides perfect techniques to achieve what you want: templates and
> static configuration are very powerful tools to provide both flexibility
> and good design.
> Stefan
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