nullable_traits<T> defines how to treat a T as “nullable” without an external engaged bit.
Declared in <mrdocs/ADT/Nullable.hpp>
template<class T>
struct nullable_traits;This trait is the canonical place to encode nullability semantics used by any optional-like type.
It exposes the minimal operations needed by an optional:
is_null(const T&): test if a value is null.
null(): create a null value.
make_null(T&): turn an existing value into null.
Users may explicitly specialize nullable_traits for their types to define the desired semantics.
| Name | Description |
|---|---|
nullable_traits<Location> | nullable_traits specialization for Location. |
nullable_traits<T> | nullable_traits for types with a sentinel. |
nullable_traits<Polymorphic<T>> | nullable_traits for Polymorphic<T>. |