[Boost-users] [operator] Can't figure out syntax

25 Apr 2008

      Assuming I have a class like the following:

template <typename T>
struct point : boost::additive<point<T>, T>
{
    T x_;
    T y_;

    explicit point(T x=0, T y=0) : x_(x), y_(y)
    { }

    operator += (T offset)
    {
        x_ += offset;
        y_ += offset;
    }

    operator -= (T offset)
    {
        x_ -= offset;
        y_ -= offset;
    }
}

Now I want to change the addition and subtraction operators to allow for 
different types using the following template

class point ...

    template <typename U>
    operator += (U offset)
    {
        x_ += offset;
        y_ += offset;
    }

    template <typename U>
    operator -= (T offset)
    {
        x_ -= offset;
        y_ -= offset;
    }

...

I cannot figure out how to write the proper syntax for the boost::additive 
class, so that it generates the proper additional operators for all type 
combinations. Is that possible, at all?

Thanks, Peter