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 <utility> // for std::move()
template<typename T, typename... Types>
VariantChoice<T, Types...>::VariantChoice(T const& value) {
// place value in buffer and set type discriminator:
new(getDerived().getRawBuffer()) T(value);
getDerived().setDiscriminator(Discriminator);
}
template<typename T, typename... Types>
VariantChoice<T, Types...>::VariantChoice(T&& value) {
// place moved value in buffer and set type discriminator:
new(getDerived().getRawBuffer()) T(std::move(value));
getDerived().setDiscriminator(Discriminator);
}