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 <exception>
class EmptyVariant : public std::exception {
};
template<typename... Types>
template<typename T>
T& Variant<Types...>::get() & {
if (empty()) {
throw EmptyVariant();
}
assert(is<T>());
return *this->template getBufferAs<T>();
}