One approach to implementing tuples is using multiple-inheritance. The tuple-elements are held by leaf-classes, and the tuple class itself inherits from multiple leafs. In pseudo-code:
template<typename T0, typename T1, ..., typename Tn>
class PseudoTuple : TupleLeaf<0, T0>, TupleLeaf<1, T1>, ..., TupleLeaf<n, Tn> {
...
};
Each leaf has an index, so that each base-class becomes unique even if the types they contain are identical, so we can access the nth element with a simple static_cast:
static_cast<TupleLeaf<0, T0>*>(this);
// ...
static_cast<TupleLeaf<n, Tn>*>(this);
I’ve written up a detailed explanation about this “flat” tuple implementation here: C++11 tuple implementation details (Part 1)
