Branching on builtin_type ()

[Jordi Gutiérrez Hermoso]

While reading Jaroslav's code, I frequently come across constructs
like this one:

          switch (argx.builtin_type ())
            {
            case btyp_double:
              retval = argx.array_value ().nth_element (n, dim);
              break;
            case btyp_float:
              retval = argx.float_array_value ().nth_element (n, dim);
              break;
            case btyp_complex:
              retval = argx.complex_array_value ().nth_element (n, dim);
              break;
            case btyp_float_complex:
              retval = argx.float_complex_array_value ().nth_element (n, dim);
              break;
    #define MAKE_INT_BRANCH(X) \
            case btyp_ ## X: \
              retval = argx.X ## _array_value ().nth_element (n, dim); \
              break

            MAKE_INT_BRANCH (int8);
            MAKE_INT_BRANCH (int16);
            MAKE_INT_BRANCH (int32);
            MAKE_INT_BRANCH (int64);
            MAKE_INT_BRANCH (uint8);
            MAKE_INT_BRANCH (uint16);
            MAKE_INT_BRANCH (uint32);
            MAKE_INT_BRANCH (uint64);
    #undef MAKE_INT_BRANCH
            default:
              if (argx.is_cellstr ())
                retval = argx.cellstr_value ().nth_element (n, dim);
              else
                gripe_wrong_type_arg ("nth_element", argx);
            }

This is from data.cc:6415 @ rev ec660526ae50.

Can't this be improved? This manual polymorphism is error-prone and
ugly to read. Isn't there an abstract array type that one can convert
an octave_value into and then call virtual functions on this type?

TIA,
- Jordi G. H.