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- [/
- Copyright 2007 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_base_of is_base_of]
- template <class Base, class Derived>
- struct is_base_of : public __tof {};
-
- __inherit If Base is base class of type Derived or if both types are the same
- class type then inherits from __true_type,
- otherwise inherits from __false_type.
- This template will detect non-public base classes, and ambiguous base classes.
- It also detects indirect base classes - which is to say __is_base_of<B, D> inherits
- from __true_type if B is located anywhere in the inheritance tree of D.
- Note that `is_base_of<X,X>` will inherit from __true_type if X is a class type.
- This is a change in behaviour
- from Boost-1.39.0 in order to track the emerging C++0x standard.
- Types `Base` and `Derived` must not be incomplete types.
- __std_ref 10.
- __header ` #include <boost/type_traits/is_base_of.hpp>` or ` #include <boost/type_traits.hpp>`
- [all_compilers]
- __examples
- [:Given: ` class Base{}; class Derived : public Base{};` ]
- [:`is_base_of<Base, Derived>` inherits from `__true_type`.]
- [:`is_base_of<Base, Derived>::type` is the type `__true_type`.]
- [:`is_base_of<Base, Derived>::value` is an integral constant
- expression that evaluates to /true/.]
- [:`is_base_of<Base, Base>::value` is an integral constant
- expression that evaluates to /true/: a class is regarded as it's own base.]
- [:`is_base_of<T, T>::value_type` is the type `bool`.]
- [endsect]
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