Eo base: Change parent_set to be an assignment of ref.

After this change, parent_set assigns a ref, so for example:
  obj = eo_add(CLASS, parent); /* Ref is 1 */
  eo_do(obj, eo_parent_set(parent2)); /* Ref is 1 */
  eo_ref(obj); /* Ref is 2 */
  eo_do(obj, eo_parent_set(NULL)); /* Ref is 1, giving the ref to NULL */
  eo_do(obj, eo_parent_set(parent)); /* Ref is 1 */

This is following a discussion on the ML about commit
8689d54471aafdd7a5b5a27ce116bf2ab68c1042.

@feature

3 files changed, 32 insertions, 5 deletions

diff --git a/src/lib/eo/eo.c b/src/lib/eo/eo.c
index b5e24a91a5..4cd992dc71 100644
--- a/src/lib/eo/eo.c
+++ b/src/lib/eo/eo.c
@@ -917,13 +917,13 @@ _eo_add_internal_start(const char *file, int line, const Eo_Class *klass_id, Eo
 
    eo_do(eo_id, eo_parent_set(parent_id));
 
-   /* If there's a parent. Unref. Eo_add should return an object with either a
+   /* If there's a parent. Ref. Eo_add should return an object with either a
     * parent ref, or with the lack of, just a ref. */
      {
         Eo *parent_tmp;
-        if (!ref && eo_do_ret(eo_id, parent_tmp, eo_parent_get()))
+        if (ref && eo_do_ret(eo_id, parent_tmp, eo_parent_get()))
           {
-             _eo_unref(obj);
+             _eo_ref(obj);
           }
      }
 
diff --git a/src/lib/eo/eo_base_class.c b/src/lib/eo/eo_base_class.c
index 0c5f3ef01d..bbdf426ee7 100644
--- a/src/lib/eo/eo_base_class.c
+++ b/src/lib/eo/eo_base_class.c
@@ -124,7 +124,12 @@ _eo_base_parent_set(Eo *obj, Eo_Base_Data *pd, Eo *parent_id)
              ERR("CONTACT DEVS!!! SHOULD NEVER HAPPEN!!! Old parent %p for object %p is not a valid Eo object.",
                  pd->parent, obj);
           }
-        eo_unref(obj);
+
+        /* Only unref if we don't have a new parent instead. */
+        if (!parent_id)
+          {
+             eo_unref(obj);
+          }
      }
 
    /* Set new parent */
@@ -138,7 +143,6 @@ _eo_base_parent_set(Eo *obj, Eo_Base_Data *pd, Eo *parent_id)
              pd->parent = parent_id;
              parent_pd->children = eina_list_append(parent_pd->children, obj);
              pd->parent_list = eina_list_last(parent_pd->children);
-             eo_ref(obj);
           }
         else
           {
diff --git a/src/tests/eo/suite/eo_test_general.c b/src/tests/eo/suite/eo_test_general.c
index 47064cf373..9121f8fac0 100644
--- a/src/tests/eo/suite/eo_test_general.c
+++ b/src/tests/eo/suite/eo_test_general.c
@@ -464,6 +464,29 @@ START_TEST(eo_refs)
    ck_assert_int_eq(eo_ref_get(obj2), 1);
    ck_assert_int_eq(eo_ref_get(obj3), 2);
 
+   /* Setting and removing parents. */
+   obj = eo_add(SIMPLE_CLASS, NULL);
+   obj2 = eo_ref(eo_add(SIMPLE_CLASS, obj));
+   obj3 = eo_ref(eo_add(SIMPLE_CLASS, NULL));
+
+   eo_do(obj2, eo_parent_set(obj3));
+   eo_do(obj3, eo_parent_set(obj));
+   ck_assert_int_eq(eo_ref_get(obj2), 2);
+   ck_assert_int_eq(eo_ref_get(obj3), 2);
+
+   eo_do(obj2, eo_parent_set(NULL));
+   eo_do(obj3, eo_parent_set(NULL));
+   ck_assert_int_eq(eo_ref_get(obj2), 1);
+   ck_assert_int_eq(eo_ref_get(obj3), 1);
+
+   eo_do(obj2, eo_parent_set(obj));
+   eo_do(obj3, eo_parent_set(obj));
+   ck_assert_int_eq(eo_ref_get(obj2), 1);
+   ck_assert_int_eq(eo_ref_get(obj3), 1);
+
+   eo_del(obj);
+   eo_del(obj2);
+   eo_del(obj3);
 
    /* Just check it doesn't seg atm. */
    obj = eo_add(SIMPLE_CLASS, NULL);