Type Classification

The following structs implement classification as defined by section 3.9 in the C++ standard. All types can be classified into one of ten basic categories:

• integral
• floating
• void
• pointer
• member pointer
• reference
• array
• enum
• union
• class

Top level cv qualifications do not affect type classification. For example, both const int and int are considered to be of integral type.

  bool b = is_XXX<T>::value;
  

where is_XXX is one of the ten basic categories.

• is_integral
• is_floating
• is_void
• is_pointer
• is_member_pointer
• is_reference
• is_array
• is_enum
• is_union
• is_class

There are also five categories that are made up of combinations of the ten basic categories:

• is_arithmetic - is_integral or is_floating
• is_fundamental - is_arithmetic or is_void
• is_scalar - is_arithmetic or is_pointer or is_member_pointer or is_enum
• is_compound - not is_fundamental
• is_object - anything but a void or reference type

The classifications: is_enum and is_union do not currently work automatically. Enumerations and unions will be mistakenly classified as class type. This can be corrected on a case by case basis by specializing is_enum_imp or is_union_imp. These specializations are in the Metrowerks::details namespace.

is_extension is also provided for those types that we provide as an extension to the C++ standard. is_extension<T>::value will be false for all types except for long long and unsigned long long.

has_extension is a modified form of is_extension that answers to true if a type is either an extension or contains an extension.

bool b = is_integral<volatile int>::value;
The value of b is true.

enum MyEnum {zero, one, two};
 
template <>

struct Metrowerks::details::is_enum_imp<MyEnum>

   {static const bool value = true;};

is_extension<long long*&>::value;    // false
has_extension<long long*&>::value;   // true

• is_signed / is_unsigned