PyAPI: Store PyInstances for ID's

This means once an ID is created,
it will keep using the same PyObject instance.

This has some advantages:
- Avoids unnecessary re-creation of instances on UI poll / redraw.
- Accessing free'd ID's gives an exception instead of crashing.
  (long standing annoyance!, though this only applies to ID's
   and not yet other data that uses the ID's - vertices for eg).
- Allows using instance comparison (a little faster).

Note that the instances won't be kept between undo.

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_internal.h b/source/blender/makesrna/intern/rna_internal.h
index 577c2853201..00b1b53ad71 100644
--- a/source/blender/makesrna/intern/rna_internal.h
+++ b/source/blender/makesrna/intern/rna_internal.h
@@ -221,6 +221,7 @@ void rna_ID_name_set(struct PointerRNA *ptr, const char *value);
 struct StructRNA *rna_ID_refine(struct PointerRNA *ptr);
 struct IDProperty *rna_ID_idprops(struct PointerRNA *ptr, bool create);
 void rna_ID_fake_user_set(struct PointerRNA *ptr, int value);
+void **rna_ID_instance(PointerRNA *ptr);
 struct IDProperty *rna_PropertyGroup_idprops(struct PointerRNA *ptr, bool create);
 void rna_PropertyGroup_unregister(struct Main *bmain, struct StructRNA *type);
 struct StructRNA *rna_PropertyGroup_register(struct Main *bmain, struct ReportList *reports, void *data,