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is_pod

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

Inherits: If T is a (possibly cv-qualified) POD type then inherits from true_type, otherwise inherits from false_type.

POD stands for "Plain old data". Arithmetic types, and enumeration types, a pointers and pointer to members are all PODs. Classes and unions can also be POD's if they have no non-static data members that are of reference or non-POD type, no user defined constructors, no user defined assignment operators, no private or protected non-static data members, no virtual functions and no base classes. Finally, a cv-qualified POD is still a POD, as is an array of PODs.

C++ Standard Reference: 3.9p10 and 9p4 (Note that POD's are also aggregates, see 8.5.1).

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, ispod will never report that a class or struct is a POD; this is always safe, if possibly sub-optimal. Currently (May 2005) only MWCW 9 and Visual C++ 8 have the necessary compiler-_intrinsics.

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

Examples:

is_pod<int> inherits from true_type.

is_pod<char*>::type is the type true_type.

is_pod<int (*)(long)>::value is an integral constant expression that evaluates to true.

is_pod<MyClass>::value is an integral constant expression that evaluates to false.

is_pod<T>::value_type is the type bool.


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