[Zope] index_object() and bobobase_modification_time with different ZCatalogs

Hello, does anybody knows a different possibility to beware the bobobase_modification_time of the given object from the following code? def my_index_object(object, catalogs=['myPointerCatalog', 'mySearchCatalog']): for cat in catalogs: object.default_catalog = cat object.index_object() # set back to default object.default_catalog = 'Catalog' regards jens