| [/ |
| 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_abstract is_abstract] |
| template <class T> |
| struct is_abstract : public __tof {}; |
| |
| __inherit If T is a (possibly cv-qualified) abstract type then inherits from |
| __true_type, otherwise inherits from __false_type. |
| |
| __std_ref 10.3. |
| |
| __header ` #include <boost/type_traits/is_abstract.hpp>` or ` #include <boost/type_traits.hpp>` |
| |
| __compat The compiler must support DR337 (as of April 2005: GCC 3.4, VC++ 7.1 (and later), |
| Intel C++ 7 (and later), and Comeau 4.3.2). |
| Otherwise behaves the same as __is_polymorphic; |
| this is the "safe fallback position" for which polymorphic types are always |
| regarded as potentially abstract. The macro BOOST_NO_IS_ABSTRACT is used to |
| signify that the implementation is buggy, users should check for this in their |
| own code if the "safe fallback" is not suitable for their particular use-case. |
| |
| __examples |
| |
| [:Given: `class abc{ virtual ~abc() = 0; };` ] |
| |
| [:`is_abstract<abc>` inherits from `__true_type`.] |
| |
| [:`is_abstract<abc>::type` is the type `__true_type`.] |
| |
| [:`is_abstract<abc const>::value` is an integral constant |
| expression that evaluates to /true/.] |
| |
| [:`is_abstract<T>::value_type` is the type `bool`.] |
| |
| [endsect] |
| |