is_virtual_base_of

template <class Base, class Derived>
struct is_virtual_base_of : public true_type-or-false_type {};

Inherits: If Base is a virtual base class of type Derived then inherits from true_type, otherwise inherits from false_type.

Types Base and Derived must not be incomplete types.

C++ Standard Reference: 10.

Header: #include <boost/type_traits/is_virtual_base_of.hpp> or #include <boost/type_traits.hpp>

Compiler Compatibility: All current compilers are supported by this trait.

	Note
	There are a small number of cases where it's simply not possible for this trait to work, and where attempting to instantiate the trait will cause compiler errors (see bug reports #3730 and 11323). Further more the issues may well be compiler specific. In this situation the user should supply a full specialization of the trait to work around the problem.

Examples:

Given: class Base{}; class Derived : public virtual Base{};

is_virtual_base_of<Base, Derived> inherits from true_type.

is_virtual_base_of<Base, Derived>::type is the type true_type.

is_virtual_base_of<Base, Derived>::value is an integral constant expression that evaluates to true.

is_virtual_base_of<SomeClassType, SomeClassType>::value is an integral constant expression that evaluates to true.

is_virtual_base_of<NotAClassType, NotAClassType>::value is an integral constant expression that evaluates to false.

is_virtual_base_of<T, U>::value_type is the type bool.

Boost C++ Libraries