stdissameT

stdissameT is a term that appears in some C++ code bases as a type-trait wrapper or alias intended to determine whether two types are exactly the same at compile time. It is not part of the official C++ standard library; when encountered, it is typically defined locally as a convenience alias or as a small custom trait around the standard std::is_same.

In practice, stdissameT<T, U> is used to yield a compile-time boolean indicating type identity. A common implementation mirrors std::is_same: it can be defined as a template struct with a static member value, or as a type alias for std::is_same. For example, a custom form might be implemented as a two-parameter template that exposes a boolean value called value; or simply forward to std::is_same<T, U>::value. In modern code, many projects prefer using std::is_same directly, or a constexpr boolean alias for brevity.

Usage and applications: stdissameT is useful in template metaprogramming, such as enabling or constraining templates with static_assert or enable_if, based on exact type matches. Example usage might include static_assert(stdissameT<int, int>::value, "types must be identical"); or in enable_if conditions to select overloads when two types are the same.

Notes and limitations: Since stdissameT is not standardized, its behavior depends on its local definition. When defining or using such a trait, ensure compatibility with cv-qualifiers and reference types, as these aspects affect type identity in templates. The standard equivalent is std::is_same<T, U> from <type_traits>.

See also: std::is_same, type_traits, template metaprogramming.