Checking for null
| Appendix A. The RefPtr smartpointer |

## Checking for null

Just like normal pointers, you can check whether a `RefPtr` points to anything.

    Glib::RefPtr<Gtk::TreeModel> refModel = m_TreeView.get_model();
    if(refModel)
    {
      int cols_count = refModel->get_n_columns();
      ...
    }

But unlike normal pointers, `RefPtr`s are automatically initialized to null so you don't need to remember to do that yourself.

Casting |  | Constness