error when a python operator gave an incorrect return value was near useless, re-raise a more comprehensive error which includes the operator name.

2 files changed, 16 insertions, 2 deletions

diff --git a/source/blender/python/intern/bpy_operator.c b/source/blender/python/intern/bpy_operator.c
index 7310878f661..742dce30124 100644
--- a/source/blender/python/intern/bpy_operator.c
+++ b/source/blender/python/intern/bpy_operator.c
@@ -293,7 +293,7 @@ static PyObject *pyop_call(PyObject *UNUSED(self), PyObject *args)
 	 * function corrects bpy.data (internal Main pointer) */
 	BPY_modules_update(C);
 
-	/* needed for when WM_OT_read_factory_settings us called fro within a script */
+	/* needed for when WM_OT_read_factory_settings us called from within a script */
 	bpy_import_main_set(CTX_data_main(C));
 
 	/* return operator_ret as a bpy enum */
diff --git a/source/blender/python/intern/bpy_rna.c b/source/blender/python/intern/bpy_rna.c
index 17992fdae31..a3ff4314002 100644
--- a/source/blender/python/intern/bpy_rna.c
+++ b/source/blender/python/intern/bpy_rna.c
@@ -6417,7 +6417,21 @@ static int bpy_class_call(bContext *C, PointerRNA *ptr, FunctionRNA *func, Param
 			err= -1;
 		}
 		else if(ret_len==1) {
-			err= pyrna_py_to_prop(&funcptr, pret_single, retdata_single, ret, "calling class function:");
+			err= pyrna_py_to_prop(&funcptr, pret_single, retdata_single, ret, "");
+
+			/* when calling operator funcs only gives Function.result with
+			 * no line number since the func has finished calling on error,
+			 * re-raise the exception with more info since it would be slow to
+			 * create prefix on every call (when there are no errors) */
+			if(err == -1 && PyErr_Occurred()) {
+				PyObject *error_type, *error_value, *error_traceback;
+				PyErr_Fetch(&error_type, &error_value, &error_traceback);
+
+				PyErr_Format(error_type,
+				             "expected class %.200s, function %.200s: incompatible return value%S",
+				             RNA_struct_identifier(ptr->type), RNA_function_identifier(func),
+				             error_value);
+			}
 		}
 		else if (ret_len > 1) {