boost_1_45_0/libs/type_traits/doc/is_virtual_base_of.qbk

[/ 
  Copyright 2009 John Maddock.
  Distributed under the Boost Software License, Version 1.0.
  (See accompanying file LICENSE_1_0.txt or copy at
  http://www.boost.org/LICENSE_1_0.txt).
]

[section:is_virtual_base_of is_virtual_base_of]
   template <class Base, class Derived>
   struct is_virtual_base_of : public __tof {};
  
__inherit 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.

__std_ref 10.

__header ` #include <boost/type_traits/is_virtual_base_of.hpp>` or ` #include <boost/type_traits.hpp>`

__compat this trait also requires a working __is_base_of trait.

__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<Base, Derived>::value` is an integral constant 
expression that evaluates to /true/.]

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

[endsect]