Function make_class_by_base 

pub unsafe fn make_class_by_base(
    class_name: *const i8,
    pkg_name: *const i8,
    base: RBase,
) -> R_altrep_class_t

Create an ALTREP class handle based on the runtime base type.

Validates the returned handle and panics if registration fails.

Safety

Must be called during R initialization (after set_altrep_dll_info).