[pygi] don't error out on methods with callbacks as return type

[John Palmieri <johnp src gnome org>]

commit e928ea9b1df9d87314ff8e93479530e26be9bd87
Author: John (J5) Palmieri <johnp redhat com>
Date:   Fri May 14 14:57:27 2010 -0400

    don't error out on methods with callbacks as return type
    
    * Right now we just throw an error which means API's like
      gtk_about_dialog_set_url_hook aren't able to be called,
    * this allows us to call such APIs while printing a warning, in most cases
      API such as this doesn't need to be used anymore and is a result of
      early GTK development

 gi/pygi-argument.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)
---
diff --git a/gi/pygi-argument.c b/gi/pygi-argument.c
index 57547a0..930df31 100644
--- a/gi/pygi-argument.c
+++ b/gi/pygi-argument.c
@@ -1433,9 +1433,17 @@ _pygi_argument_to_object (GArgument  *arg,
             switch (info_type) {
                 case GI_INFO_TYPE_CALLBACK:
                 {
-                    PyErr_SetString(PyExc_NotImplementedError, "callback marshalling is not supported yet");
-                    /* TODO */
-                    break;
+                  /* There is no way we can support a callback return
+                   * as we are never sure if the callback was set from C
+                   * or Python.  API that return callbacks are broken
+                   * so we print a warning and send back a None
+                   */
+
+                  g_warning("You are trying to use an API which returns a callback."
+                            "Callback returns can not be supported. Returning None instead.");
+                  object = Py_None;
+                  Py_INCREF(object);
+                  break;
                 }
                 case GI_INFO_TYPE_BOXED:
                 case GI_INFO_TYPE_STRUCT: