Boost C++ Libraries

template <class T>
struct is_stateless : public true_type-or-false_type {};

Inherits: Ff T is a stateless type then inherits from true_type, otherwise from false_type.

Type T must be a complete type.

A stateless type is a type that has no storage and whose constructors and destructors are trivial. That means that is_stateless only inherits from true_type if the following expression is true:

::boost::has_trivial_constructor<T>::value
&& ::boost::has_trivial_copy<T>::value
&& ::boost::has_trivial_destructor<T>::value
&& ::boost::is_class<T>::value
&& ::boost::is_empty<T>::value

C++ Standard Reference: 3.9p10.

Header: #include <boost/type_traits/is_stateless.hpp> or #include <boost/type_traits.hpp>

Compiler Compatibility: If the compiler does not support partial-specialization of class templates, then this template can not be used with function types.

Without some (as yet unspecified) help from the compiler, is_stateless will never report that a class or struct is stateless; this is always safe, if possibly sub-optimal. Currently (May 2005) only MWCW 9 and Visual C++ 8 have the necessary compiler intrinsics to make this template work automatically.