Classification of template typename labels?

From: Ralf W. Grosse-Kunstleve (rwgk_at_[hidden])
Date: 2002-01-20 08:33:19

(This question is related to my previous posting.)

Here is something I am often wondering about:

template <typename NumVectorType>
NumVectorType operator*(const NumVectorType& lhs, const NumVectorType& rhs);

Is there a way to classify or register types as NumVectorTypes?

I know how to make a distinction between types once I am
/inside/ the function (using traits). However, what I am
after is something like:

tell_compiler {
  possible typename NumType:
    double
    float
    etc.
  possible typename NumVectorType:
    std::vector<NumType>
    boost::array<NumType, *>
    etc.
}

Then the compiler should select template functions only if the
concrete type is registered under the typename label.

Is this asking for a formalization of "concepts?"
To which degree can this be emulated with the language as-is?
What can we expect in the future (from the standard committee)?

Thanks,
        Ralf