libs/type_traits/doc/has_bit_and.qbk
[/ (C) Copyright 2009-2011 Frederic Bron. 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:has_bit_and has_bit_and] template <class Lhs, class Rhs=Lhs, class Ret=dont_care> struct has_bit_and : public __tof {}; __inherit If (i) `lhs` of type `Lhs` and `rhs` of type `Rhs` can be used in expression `lhs&rhs`, and (ii) `Ret=dont_care` or the result of expression `lhs&rhs` is convertible to `Ret` then inherits from __true_type, otherwise inherits from __false_type. The default behaviour (`Ret=dont_care`) is to not check for the return value of binary `operator&`. If `Ret` is different from the default `dont_care` type, the return value is checked to be convertible to `Ret`. Convertible to `Ret` means that the return value of the operator can be used as argument to a function expecting `Ret`: `` void f(Ret); Lhs lhs; Rhs rhs; f(lhs&rhs); // is valid if has_bit_and<Lhs, Rhs, Ret>::value==true `` If `Ret=void`, the return type is checked to be exactly `void`. __header `#include <boost/type_traits/has_bit_and.hpp>` or `#include <boost/type_traits/has_operator.hpp>` or `#include <boost/type_traits.hpp>` __examples [:`has_bit_and<Lhs, Rhs, Ret>::value_type` is the type `bool`.] [:`has_bit_and<Lhs, Rhs, Ret>::value` is a `bool` integral constant expression.] [:`has_bit_and<int>::value` is a `bool` integral constant expression that evaluates to `true`.] [:`has_bit_and<long>` inherits from `__true_type`.] [:`has_bit_and<int, int, int>` inherits from `__true_type`.] [:`has_bit_and<const int, int>` inherits from `__true_type`.] [:`has_bit_and<int, double, bool>` inherits from `__false_type`.] [:`has_bit_and<int, int, std::string>` inherits from `__false_type`.] [*See also:] [link boost_typetraits.category.value_traits.operators Operator Type Traits] [has_binary_operator_compat] [binary_operator_known_issues has_bit_and..&..A..contains<T>..const ] [endsect]