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From: David Bergman (davidb_at_[hidden])
Date: 2004-04-02 13:17:26

Peter Dimov wrote:

> David Bergman wrote:
> >
> > On the meta level, a trait places a Concept in relation to other
> > Concepts, i.e., a trait is STRUCTURAL. On the object-level,
> a Model is
> > related to other Models or Features.
> >
> > trait<Type>::neighbor_type - relates two Concepts
> > trait<Type>::child_type - adds a Feature
> >
> > A policy is BEHAVIORAL. And one often uses policies in a dynamic
> > setting, adding them in runtime. We, of course, often
> implicitly refer
> > to the compile-time policies...
> So...
> In A<X>::frobnicate(), 'A' is a policy, because it's
> behavioral, and in

No, A is not behavioral. The feature "frobnicate" of the type X is. And,
that mapped behaviors can definitely be used as a policy.
> template<class B> struct X
> {
> template typename B::value_type value_type; };
> 'B' is a trait, because it's structural?

No, since a trait not only has to be structural, but *also* be a (set of)
meta functions with the Concept as a range.


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