Question

I have a Kd-Tree implementation, which is templatized to accept any dimension greater than 0 and any floating-point type (float, double, etc…). Something like this:

template <typename real, size_t dimensions> class KdTree
{
    // stuff
}

And I have an accompanying “point” type which has the exact same template layout. However this point type needs to be accessible from outside the kd-tree class. Now, every time I need to create temporary points inside my kd-tree code, I need to explicitly go KdPoint<real, dimensions>, which is tiresome, makes my lines really long, and adds no value whatsoever to the code.

Is there any way I can tell the compiler to implicitly assume whatever values for real and dimensions were passed to the class for the points as well? Linking the two template lists together, in a way. So that I can just type KdPoint and the compiler will directly know what to put in there, based on the template arguments the class received.

Otherwise I’ll need to use a macro to explicitly expand the latter into the former, which kind of sucks.

Answer 1

You could add a typedef to the KdTree class:

template <typename real, size_t dimensions> class KdTree
{
  typedef KdPoint<real, dimensions> KdPoint_;
  // stuff
};

and use KdPoint_ internally. If you want the point type to be accessible externally, give the typedef public access, and a name that doesn-t end in _:

template <typename real, size_t dimensions> class KdTree
{
 public:
  typedef KdPoint<real, dimensions> KdPointType;
  // stuff
};

This can then be accessed like this:

KdTree<float, 5>::KdPointType