better error message with requirementerror

tiramisu/setting.py

@@ -673,12 +673,16 @@ class Settings(object):
                                 continue
                         properties = value.proptype
                         if same_action and action not in properties:  # pragma: optional cover
-                            raise RequirementError(_("option '{0}' has "
-                                                     "requirement's property "
-                                                     "error: "
-                                                     "{1} {2}").format(opt._name,
-                                                                       reqpath,
-                                                                       properties))
+                            if len(properties) == 1:
+                                prop_msg = _('property')
+                            else:
+                                prop_msg = _('properties')
+                            raise RequirementError(_('cannot access to option "{0}" because '
+                                                     'required option "{1}" has {2} {3}'
+                                                     '').format(opt.impl_get_display_name(),
+                                                                option.impl_get_display_name(),
+                                                                prop_msg,
+                                                                display_list(properties)))
                         orig_value = value
                         # transitive action, force expected
                         value = expected[0]