Question

I have a function that handles two types: NVector and NMatrix; the former is derived from the latter. This function is basically a specialized copy constructor. I want it to return an object of the same type as that upon which it was called, so, NVector returns NVector, not NMatrix.

static VALUE nm_init_modifiedcopy(VALUE self) {
  // ... some code ...

  // formerly, I had cNMatrix where klass is. But it could also be cNVector!
  return Data_Wrap_Struct(klass, mark_func, delete_func, unwrapped_self_copy);
}

How do I get the class property of an object to pass into Data_Wrap_Struct?

Answer 1

Like clockwork, as soon as I ask a question on Stackoverflow, I find the answer.

The macro is CLASS_OF.

static VALUE nm_init_modifiedcopy(VALUE self) {
  // ... some code ...

  return Data_Wrap_Struct(CLASS_OF(self), mark_func, delete_func, unwrapped_self_copy);
}