[PATCH v2 09/10] qom: Allow default values for instance properties

ObjectProperty allows default value settings via proper setup of
prop->init() and prop->defval.  It currently is only supported in class
properties, not instance properties.

However, since QOM allows class and instance properties, it should also
allow instance to add properties during instance_init() and allow the
default values to be applied properly for this instance only.

Add the logic.  It will be useful for all kinds of pointer based properties
because pointers are normally not accessble in a class but only when an
instance is available.  This will be able to achieve similar function as
what qdev properties have (which works by remembering offsets within a
structure instead).

Signed-off-by: Peter Xu <[email protected]>
---
 qom/object.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/qom/object.c b/qom/object.c
index fc738549dc..eaef615924 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -487,6 +487,20 @@ static void object_class_property_init_all(Object *obj)
     }
 }
 
+static void object_property_init_all(Object *obj)
+{
+    GHashTableIter iter;
+    gpointer key, val;
+
+    g_hash_table_iter_init(&iter, obj->properties);
+    while (g_hash_table_iter_next(&iter, &key, &val)) {
+        ObjectProperty *prop = val;
+        if (prop->init) {
+            prop->init(obj, prop);
+        }
+    }
+}
+
 static void object_initialize_with_type(Object *obj, size_t size, TypeImpl *type)
 {
     type_initialize(type);
@@ -498,10 +512,22 @@ static void object_initialize_with_type(Object *obj, size_t size, TypeImpl *type
     memset(obj, 0, type->instance_size);
     obj->class = type->class;
     object_ref(obj);
+    /*
+     * A few steps to initialize properties for the objects:
+     *
+     * (1) apply default values from class properties when available
+     * (2) invoke instance_init(), which may add per-instance properties,
+     *     which may further contain default values
+     * (3) apply default values from instance properties when available
+     *
+     * instance_post_init() should happen at last, after the instance is
+     * fully initialized.
+     */
     object_class_property_init_all(obj);
     obj->properties = g_hash_table_new_full(g_str_hash, g_str_equal,
                                             NULL, object_property_free);
     object_init_with_type(obj, type);
+    object_property_init_all(obj);
     object_post_init_with_type(obj, type);
 }
 
-- 
2.53.0