Rob Stewart <stewart@sig.com> writes:
From: David Abrahams <dave@boost-consulting.com>
Technically one can never say "class template foo is a traits template" or "class template foo is a policy" without examining how it's used. There's no fundamental reason that the same class template can't be used in both ways, so for any given class template, there may be no either/or answer.
I don't quite agree. A policy class is only that because it is a template parameter.
A class is never a template parameter. It can be a template argument.
Whether a class that is passed as a policy to some template happens to be a traits class is immaterial. So, in the context of the template, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Exactly. How it's used.
the template parameter is a policy class and that may correspond to a traits class in a particular specialization, but that doesn't make the traits class a policy class. Does that make sense?
Not much, to me. I think you're trying to say the same thing I said, but in a more contorted way. -- Dave Abrahams Boost Consulting www.boost-consulting.com