Eo: Add a method to mark objects for reuse.

This informas eo an object is going to get reused/cached, so eo can
reset the object appropriately.

@feature.

src/lib/eo/Eo.h

@@ -1096,6 +1096,17 @@ EAPI void efl_del_intercept_set(Eo *obj, Efl_Del_Intercept del_intercept_func);
  */
 EAPI Efl_Del_Intercept efl_del_intercept_get(const Eo *obj);
 
+/**
+ * @brief Clears the object so it can be reused (for example in a cache)
+ * @param obj The object to mark for reusal
+ *
+ * This assumes the destructor has been called on the object, so it
+ * should probably only be used from the del intercept.
+ *
+ * @see efl_del_intercept_set()
+ */
+EAPI void efl_reuse(const Eo *obj);
+
 /**
  * @def efl_xref(obj, ref_obj)
  * Convenience macro around efl_xref_internal()

src/lib/eo/eo.c

@@ -856,7 +856,7 @@ _efl_add_end(Eo *eo_id, Eina_Bool is_ref, Eina_Bool is_fallback)
           {
              efl_ref(eo_id);
           }
-        _efl_object_parent_sink(eo_id);
+        _efl_object_parent_sink_set(eo_id, EINA_TRUE);
      }
 
    if (is_fallback)
@@ -867,6 +867,13 @@ _efl_add_end(Eo *eo_id, Eina_Bool is_ref, Eina_Bool is_fallback)
    return ret;
 }
 
+EAPI void
+efl_reuse(const Eo *_obj)
+{
+   Eo *obj = (Eo *) _obj;
+   efl_object_override(obj, NULL);
+   _efl_object_parent_sink_set(obj, EINA_FALSE);
+}
 /*****************************************************************************/
 
 EAPI const Efl_Class *

src/lib/eo/eo_base_class.c

@@ -535,10 +535,10 @@ _efl_object_del(const Eo *obj, Efl_Object_Data *pd EINA_UNUSED)
 }
 
 void
-_efl_object_parent_sink(Eo *obj)
+_efl_object_parent_sink_set(Eo *obj, Eina_Bool sink)
 {
    Efl_Object_Data *pd = efl_data_scope_get(obj, EFL_OBJECT_CLASS);
-   pd->parent_sunk = EINA_TRUE;
+   pd->parent_sunk = sink;
 }
 
 EOLIAN static void

src/lib/eo/eo_private.h

@@ -196,7 +196,7 @@ typedef struct
    int line;
 } Eo_Xref_Node;
 
-void _efl_object_parent_sink(Eo *obj);
+void _efl_object_parent_sink_set(Eo *obj, Eina_Bool sink);
 
 static inline
 Eo *_eo_header_id_get(const Eo_Header *header)

src/tests/eo/suite/eo_test_general.c

@@ -1230,6 +1230,12 @@ _del_intercept(Eo *obj)
    efl_del_intercept_set(obj, NULL);
    efl_unref(obj);
 }
+
+static void
+_del_intercept_reuse(Eo *obj)
+{
+   efl_reuse(obj);
+}
 #endif
 
 START_TEST(efl_del_intercept)
@@ -1270,6 +1276,21 @@ START_TEST(efl_del_intercept)
    fail_if(!intercepted);
    fail_if(efl_isa(obj, klass));
 
+   /* Check reuse works as expected. */
+   Eo *parent = efl_add(SIMPLE_CLASS, NULL);
+   obj = efl_add(klass, NULL);
+   fail_if(!obj);
+   ck_assert_int_eq(efl_ref_get(obj), 1);
+   efl_parent_set(obj, parent);
+   ck_assert_int_eq(efl_ref_get(obj), 1);
+   efl_del_intercept_set(obj, _del_intercept_reuse);
+   efl_del_intercept_set(obj, NULL);
+   /* This essentially checks it get unsunk */
+   ck_assert_int_eq(efl_ref_get(obj), 1);
+   efl_parent_set(obj, parent);
+   ck_assert_int_eq(efl_ref_get(obj), 1);
+   efl_del(obj);
+
    efl_object_shutdown();
 #endif
 }