Function PyVTKObject_FromPointer

Wrapping/PythonCore/PyVTKObject.cxx:644–815

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
PyObject* PyVTKObject_FromPointer(PyTypeObject* pytype, PyObject* ghostdict, vtkObjectBase* ptr)
{
  // This will be set if we create a new C++ object
  bool created = false;
  std::string classname = vtkPythonUtil::StripModuleFromType(pytype);
  PyVTKClass* cls = nullptr;

  if (ptr)
  {
    // If constructing from an existing C++ object, use its actual class
    classname = ptr->GetClassName();
    cls = vtkPythonUtil::FindClass(classname.c_str());
  }

  if (cls == nullptr)
  {
    // Use the vtkname of the supplied class type
    PyObject* s = PyObject_GetAttrString((PyObject*)pytype, "__vtkname__");
    if (s)
    {
      PyObject* tmp = PyUnicode_AsUTF8String(s);
      if (tmp)
      {
        Py_DECREF(s);
        s = tmp;
      }
      const char* vtkname_classname = PyBytes_AsString(s);
      if (vtkname_classname == nullptr)
      {
        Py_DECREF(s);
        return nullptr;
      }
      classname = vtkname_classname;
      Py_DECREF(s);
    }
    cls = vtkPythonUtil::FindClass(classname.c_str());
    if (cls == nullptr)
    {
      PyErr_Format(PyExc_ValueError, "internal error, unknown VTK class %.200s", classname.c_str());
      return nullptr;
    }
  }

  if (!ptr)
  {
    // Create a new instance of this class since we were not given one.
    if (cls->vtk_new)
    {
      ptr = cls->vtk_new();
      if (!ptr)
      {
        // The vtk_new() method returns null when a factory class has no
        // implementation (i.e. cannot provide a concrete class instance.)
        // NotImplementedError indicates a pure virtual method call.
        PyErr_SetString(
          PyExc_NotImplementedError, "no concrete implementation exists for this class");
        return nullptr;
      }