stdissameint

stdissameint is a hypothetical type trait designed for template metaprogramming in C++. It provides a compile-time boolean indicating whether two given types are both the int type. In other words, it yields true when both template parameters are int, and false otherwise. It is not part of the standard C++ library, but it illustrates how a small, focused trait can be composed from existing type traits.

Definition and behavior

- The trait is typically implemented as a struct template that derives from std::integral_constant<bool, Value>, where Value is computed from type comparisons.

- A common form is to check both types against int, such as: template <typename T, typename U> struct stdissameint : std::integral_constant<bool, std::is_same<T,int>::value && std::is_same<U,int>::value> {}; This yields true only if T and U are both exactly int.

- Be aware that cv-qualified types (e.g., const int) do not match int under std::is_same, so additional normalization may be needed if cv-qualification should be ignored.

Usage

- The trait is used at compile time to enable or disable code paths via static_assert or SFINAE. For example: static_assert(stdissameint<int,int>::value, "both parameters are int"); static_assert(!stdissameint<int,long>::value, "not both int");

- If a broader intent is desired (checking whether a single type is int, or ignoring qualifiers), the trait can be adapted or combined with other type traits such as std::remove_cv or std::is_same<T,int>.

Relation to standard library

- stdissameint is a construct inspired by standard traits like std::is_same and std::integral_constant. In practice, developers achieve similar checks directly with standard traits, e.g., std::is_same<T,int>::value && std::is_same<U,int>::value.

Limitations

- It is a narrow utility and may be less flexible than directly using existing type traits.

- It relies on exact type matches; qualifiers and references affect the result unless normalized.