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
#include <complex>
template<typename T, typename U>
class SmallerThanT
{
public:
static constexpr bool value = sizeof(T) < sizeof(U);
};
void testTupleSort()
{
auto t1 = makeTuple(17LL, std::complex<double>(42,77), 'c', 42, 7.7);
std::cout << t1 << '\n';
auto t2 = sort<SmallerThanT>(t1); // t2 is Tuple<int,~long,~std::string>
std::cout << "sorted by size: " << t2 << '\n';
}