Re: template and inheritance

Hello,

Can you help me on this...
Is there a way to fix the problem at the end of the main?
If the two extra scalar product operator* were defined for scalar types
only, it would be perfect. Can this be possible?

I manage to merge the two first operator* using an is_base_of
type_traits tricks, but I could not fix the friend operator*. And that
was an ugly solution anyway.

Thanks
Olive

struct vect {
    int v[3];

    //dot product
    int operator *(const vect& t) const {
        int res = 0;
        for (int i = 0; i < 3; ++i)
            res += v[i] * t.v[i];
        return res;
    }
    //scalar product
    template <typename Y>
    vect operator *(const Y& t) const {
        vect res;
        for (int i = 0; i < 3; ++i)
            res.v[i] += v[i] * t;
        return res;
    }
    //scalar product in reverse order (t is the scalar value)
    template <typename Y>
    friend vect operator *(const Y& t, const vect& v) {
        return v*t;
    }
};

struct dummy {
};

int main() {
    {
        vect a;
        vect b;
        int dot = a*b; // fine
        vect c = a*2; // fine
        vect d = 2*a; // fine
    }
    {
        dummy a;
        dummy b;
        int dot = a*b; // the 3 operator* match
        dummy c = a*2; // the 3 operator* match
        dummy d = 2*a; // the 3 operator* match
    }

    return 0;
}