revert part of Tons commit r33884.

- rather then use unlink="None", just don't pass unlink as a keyword. This is more pythonic.
- added an RNA flag for properties which cant be unlinked by setting to None.

release/scripts/ui/properties_data_armature.py

@@ -43,9 +43,9 @@ class DATA_PT_context_arm(ArmatureButtonsPanel, bpy.types.Panel):
         space = context.space_data
 
         if ob:
-            layout.template_ID(ob, "data", unlink="None")
+            layout.template_ID(ob, "data")
         elif arm:
-            layout.template_ID(space, "pin_id", unlink="None")
+            layout.template_ID(space, "pin_id")
 
 
 class DATA_PT_skeleton(ArmatureButtonsPanel, bpy.types.Panel):

release/scripts/ui/properties_data_curve.py

@@ -60,9 +60,9 @@ class DATA_PT_context_curve(CurveButtonsPanel, bpy.types.Panel):
         space = context.space_data
 
         if ob:
-            layout.template_ID(ob, "data", unlink="None")
+            layout.template_ID(ob, "data")
         elif curve:
-            layout.template_ID(space, "pin_id", unlink="None") # XXX: broken
+            layout.template_ID(space, "pin_id") # XXX: broken
 
 
 class DATA_PT_shape_curve(CurveButtonsPanel, bpy.types.Panel):

release/scripts/ui/properties_data_mesh.py

@@ -71,9 +71,9 @@ class DATA_PT_context_mesh(MeshButtonsPanel, bpy.types.Panel):
         space = context.space_data
 
         if ob:
-            layout.template_ID(ob, "data", unlink="None")
+            layout.template_ID(ob, "data")
         elif mesh:
-            layout.template_ID(space, "pin_id", unlink="None")
+            layout.template_ID(space, "pin_id")
 
 
 class DATA_PT_normals(MeshButtonsPanel, bpy.types.Panel):

release/scripts/ui/properties_data_metaball.py

@@ -43,9 +43,9 @@ class DATA_PT_context_metaball(DataButtonsPanel, bpy.types.Panel):
         space = context.space_data
 
         if ob:
-            layout.template_ID(ob, "data", unlink="None")
+            layout.template_ID(ob, "data")
         elif mball:
-            layout.template_ID(space, "pin_id", unlink="None")
+            layout.template_ID(space, "pin_id")
 
 
 class DATA_PT_metaball(DataButtonsPanel, bpy.types.Panel):

release/scripts/ui/properties_object.py

@@ -37,7 +37,7 @@ class OBJECT_PT_context_object(ObjectButtonsPanel, bpy.types.Panel):
         ob = context.object
 
         if space.use_pin_id:
-            layout.template_ID(space, "pin_id", unlink="None")
+            layout.template_ID(space, "pin_id")
         else:
             row = layout.row()
             row.label(text="", icon='OBJECT_DATA')

source/blender/editors/animation/drivers.c

@@ -212,7 +212,7 @@ short ANIM_add_driver (ReportList *reports, ID *id, const char rna_path[], int a
 /* Main Driver Management API calls:
  * 	Remove the driver for the specified property on the given ID block (if available)
  */
-short ANIM_remove_driver (ReportList *reports, ID *id, const char rna_path[], int array_index, short UNUSED(flag))
+short ANIM_remove_driver (ReportList *UNUSED(reports), ID *id, const char rna_path[], int array_index, short UNUSED(flag))
 {
 	AnimData *adt;
 	FCurve *fcu;

source/blender/editors/interface/interface_templates.c

@@ -450,7 +450,7 @@ static void template_ID(bContext *C, uiLayout *layout, TemplateID *template, Str
 	}
 	
 	/* delete button */
-	if(id && (flag & UI_ID_DELETE)) {
+	if(id && (flag & UI_ID_DELETE) && (RNA_property_flag(template->prop) & PROP_NEVER_UNLINK)==0) {
 		if(unlinkop) {
 			but= uiDefIconButO(block, BUT, unlinkop, WM_OP_INVOKE_REGION_WIN, ICON_X, 0, 0, UI_UNIT_X, UI_UNIT_Y, NULL);
 			/* so we can access the template from operators, font unlinking needs this */
@@ -494,8 +494,6 @@ static void ui_template_id(uiLayout *layout, bContext *C, PointerRNA *ptr, const
 		flag |= UI_ID_ADD_NEW;
 	if(openop)
 		flag |= UI_ID_OPEN;
-	if(unlinkop && strcmp(unlinkop, "None") == 0)
-		flag &= ~UI_ID_DELETE;
 
 	type= RNA_property_pointer_type(ptr, prop);
 	template->idlb= which_libbase(CTX_data_main(C), RNA_type_to_ID_code(type));

source/blender/makesrna/RNA_types.h

@@ -167,6 +167,10 @@ typedef enum PropertyFlag {
 	 * only apply this to types that are derived from an ID ()*/
 	PROP_ID_SELF_CHECK = 1<<20,
 	PROP_NEVER_NULL = 1<<18,
+	/* currently only used for UI, this is similar to PROP_NEVER_NULL
+	 * except that the value may be NULL at times, used for ObData, where an Empty's will be NULL
+	 * but setting NULL on a mesh object is not possible. So, if its not NULL, setting NULL cant be done! */
+	PROP_NEVER_UNLINK = 1<<25,
 
 	/* flag contains multiple enums.
 	 * note: not to be confused with prop->enumbitflags

source/blender/makesrna/intern/rna_object.c

@@ -1680,7 +1680,7 @@ static void rna_def_object(BlenderRNA *brna)
 	RNA_def_property_struct_type(prop, "ID");
 	RNA_def_property_pointer_funcs(prop, NULL, "rna_Object_data_set", "rna_Object_data_typef", NULL);
 	RNA_def_property_editable_func(prop, "rna_Object_data_editable");
-	RNA_def_property_flag(prop, PROP_EDITABLE);
+	RNA_def_property_flag(prop, PROP_EDITABLE|PROP_NEVER_UNLINK);
 	RNA_def_property_ui_text(prop, "Data", "Object data");
 	RNA_def_property_update(prop, 0, "rna_Object_internal_update_data");