"Gennadiy Rozental" <gennadiy.rozental@thomson.com> wrote in message news:c4ivdk$hgl$1@sea.gmane.org...
[...] Trait is specific to the type Policy is orthogonal to the type. [...]
Where "the type", I presume, is the [template] class using the policy | trait? That sounds like a good distinction to me. May I formalize it by proposing that: 1. A trait is a metafunction of the client type. 2. A client type is a metafunction of a policy. So definition 1 means that a trait is a metafunction which maps a client type X to a specific trait type trait<X>. Definition 2 means that a policy client X is a metafunction which maps the client type to X<policy>. This makes it clear why a policy *class* need not be a template class. It also shows why a traits *client* need not be a template class. But I would welcome examples of non-template traits classes or non-template policy clients. Now, the definitions I give are necessary but not sufficient conditions for defining traits and policies. You also need to add fluff about modifying behavior, yada yada yada. Dave --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.581 / Virus Database: 368 - Release Date: 2/9/2004