template <class I,class T>
struct IndexPair : CmpComparable<IndexPair<I,T> >
 {
  I index;
  T object;

  // constuctors

  IndexPair() noexcept( Meta::HasNothrowDefaultCtor<I> && Meta::HasNothrowDefaultCtor<T> ) : index(),object() {}

  IndexPair(I index_,const T &object_) : index(index_),object(object_) {}

  // methods

  .... 
 };