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2 | Copyright 2007 John Maddock. | |
3 | Distributed under the Boost Software License, Version 1.0. | |
4 | (See accompanying file LICENSE_1_0.txt or copy at | |
5 | http://www.boost.org/LICENSE_1_0.txt). | |
6 | ] | |
7 | ||
8 | [section:is_pod is_pod] | |
9 | template <class T> | |
10 | struct is_pod : public __tof {}; | |
11 | ||
12 | __inherit If T is a (possibly cv-qualified) POD type then inherits from __true_type, | |
13 | otherwise inherits from __false_type. | |
14 | ||
15 | POD stands for "Plain old data". | |
16 | Arithmetic types, and enumeration types, | |
17 | a pointers and pointer to members are all PODs. Classes and unions can also | |
18 | be POD's if they have no non-static data members that are of reference or | |
19 | non-POD type, no user defined constructors, no user defined assignment | |
20 | operators, no private or protected non-static data members, | |
21 | no virtual functions and no base classes. Finally, a cv-qualified POD is | |
22 | still a POD, as is an array of PODs. | |
23 | ||
24 | __std_ref 3.9p10 and 9p4 (Note that POD's are also aggregates, see 8.5.1). | |
25 | ||
26 | __compat Without some (as yet unspecified) help from the compiler, is_pod will | |
27 | never report that a class or struct is a POD; this is always safe, | |
28 | if possibly sub-optimal. | |
29 | Currently (June 2015) compilers more recent than Visual C++ 8, Clang-3, GCC-4.3, Greenhills 6.0, | |
30 | Intel-11.0, and Codegear have the necessary compiler __intrinsics to ensure that this | |
31 | trait "just works". You may also test to see if the necessary __intrinsics are available | |
32 | by checking to see if the macro `BOOST_IS_POD` is defined. | |
33 | ||
34 | ||
35 | __header ` #include <boost/type_traits/is_pod.hpp>` or ` #include <boost/type_traits.hpp>` | |
36 | ||
37 | __examples | |
38 | ||
39 | [:`is_pod<int>` inherits from `__true_type`.] | |
40 | ||
41 | [:`is_pod<char*>::type` is the type `__true_type`.] | |
42 | ||
43 | [:`is_pod<int (*)(long)>::value` is an integral constant | |
44 | expression that evaluates to /true/.] | |
45 | ||
46 | [:`is_pod<MyClass>::value` is an integral constant | |
47 | expression that evaluates to /false/.] | |
48 | ||
49 | [:`is_pod<T>::value_type` is the type `bool`.] | |
50 | ||
51 | [endsect] | |
52 |