How can I use C++11 variadic templates to define a vector-of-tuples backed by a tuple-of-vectors?

Question

Suppose I have a bunch of vectors:

vector v1;
vector v2;
vector v3;

all of the same length. Now, for ev

Answer 1

An alternative to all the variadic template juggling is to use the boost::zip_iterator for this purpose. For example (untested):

std::vector ia;
std::vector d;
std::vector ib;

std::for_each(
  boost::make_zip_iterator(
    boost::make_tuple(ia.begin(), d.begin(), ib.begin())
    ),
  boost::make_zip_iterator(
    boost::make_tuple(ia.end(), d.end(), ib.end())
    ),
  handle_each()
  );

Where your handler, looks like:

struct handle_each :
  public std::unary_function&, void>
{
  void operator()(const boost::tuple& t) const
  {
    // Now you have a tuple of the three values across the vector...
  }
};

As you can see, it's pretty trivial to expand this to support an arbitrary set of vectors..