Created attachment 259147 [details] [review]
interval: Implement ClutterScriptable interface

This allows the creation of ClutterTransition objects in ClutterScript:
 {
   "id" : "scripted-transition",
   "type" : "ClutterPropertyTransition",
   "property-name" : "background-color",
   "interval" : {
     "type" : "ClutterInterval",
     "value-type" : "ClutterColor",
     "initial" : "red",
     "final" : "blue"
   }
 }

Review of attachment 259147 [details] [review]:

::: clutter/clutter-interval.c
@@ -482,0 +491,30 @@
+static gboolean
+clutter_interval_parse_custom_node (ClutterScriptable *scriptable,
+                                    ClutterScript     *script,
... 27 more ...

set_custom_property() cannot fail, so it needs to call g_object_set_property() internally otherwise setting properties that are not "initial" or "final" will not work.

I honestly don't understand how the test passes.

Review of attachment 259147 [details] [review]:

::: clutter/clutter-interval.c
@@ -482,0 +491,30 @@
+static gboolean
+clutter_interval_parse_custom_node (ClutterScriptable *scriptable,
+                                    ClutterScript     *script,
... 27 more ...

You're right, it only works because the :value-type property is construct-only and therefore handled differently.
It just won't work for potential subclasses of ClutterInterval with own properties.
I'll update the patch

Created attachment 259158 [details] [review]
interval: Implement ClutterScriptable interface

This allows the creation of ClutterTransition objects in ClutterScript:
 {
   "id" : "scripted-transition",
   "type" : "ClutterPropertyTransition",
   "property-name" : "background-color",
   "interval" : {
     "type" : "ClutterInterval",
     "value-type" : "ClutterColor",
     "initial" : "red",
     "final" : "blue"
   }
 }

Review of attachment 259158 [details] [review]:

looks good.

Pushed to clutter-1.16