is_polymorphic.qbk

来自「Boost provides free peer-reviewed portab」· QBK 代码 · 共 38 行

[/ 
  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_polymorphic is_polymorphic]
   template <class T>
   struct is_polymorphic : public __tof {};
  
__inherit If T is a (possibly cv-qualified) polymorphic type 
then inherits from __true_type, 
otherwise inherits from __false_type.  Type `T` must be a complete type.

__std_ref 10.3.

__compat The implementation requires some knowledge of the compilers ABI, 
it does actually seem to work with the majority of compilers though.

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

__examples

[: Given: `class poly{ virtual ~poly(); };` ]

[:`is_polymorphic<poly>` inherits from `__true_type`.]

[:`is_polymorphic<poly const>::type` is the type `__true_type`.]

[:`is_polymorphic<poly>::value` is an integral constant 
expression that evaluates to /true/.]

[:`is_polymorphic<T>::value_type` is the type `bool`.]

[endsect]