The following code example is taken from the book
C++ Templates - The Complete Guide, 2nd Edition
by David Vandevoorde, Nicolai M. Josuttis, and Douglas Gregor,
Addison-Wesley, 2017
© Copyright David Vandevoorde, Nicolai M. Josuttis, Douglas Gregor 2017
template<typename List, typename NewElement, bool = IsEmpty<List>::value>
class PushBackRecT;
// recursive case:
template<typename List, typename NewElement>
class PushBackRecT<List, NewElement, false>
{
using Head = Front<List>;
using Tail = PopFront<List>;
using NewTail = typename PushBackRecT<Tail, NewElement>::Type;
public:
using Type = PushFront<Head, NewTail>;
};
// basis case:
template<typename List, typename NewElement>
class PushBackRecT<List, NewElement, true>
{
public:
using Type = PushFront<List, NewElement>;
};
// generic push-back operation:
template<typename List, typename NewElement>
class PushBackT : public PushBackRecT<List, NewElement> { };
template<typename List, typename NewElement>
using PushBack = typename PushBackT<List, NewElement>::Type;