Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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is_class

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

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

C++ Standard Reference: 3.9.2 and 9.2.

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

Compiler Compatibility: Without (some as yet unspecified) help from the compiler, we cannot distinguish between union and class types, as a result this type will erroneously inherit from true_type for union types. See also is_union. Currently (May 2011) compilers more recent than Visual C++ 8, GCC-4.3, Greenhills 6.0, Intel-11.0, and Codegear have the necessary compiler intrinsics to ensure that this trait "just works". You may also test to see if the necessary intrinsics are available by checking to see if the macro BOOST_IS_CLASS is defined.

Examples:

Given: class MyClass; then:

is_class<MyClass> inherits from true_type.

is_class<MyClass const>::type is the type true_type.

is_class<MyClass>::value is an integral constant expression that evaluates to true.

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

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

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


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