...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Return true
if this is an
object.
bool is_object() const;
This function is used to determine if the underlying representation is a certain kind.
return this->kind() == kind::object;
Constant.
No-throw guarantee.