diff --git a/tiramisu/config.py b/tiramisu/config.py
index 2662ebb..2293e42 100644
--- a/tiramisu/config.py
+++ b/tiramisu/config.py
@@ -199,16 +199,22 @@ class SubConfig(object):
     # attribute methods
     def __setattr__(self, name, value):
         "attribute notation mechanism for the setting of the value of an option"
-        self._setattr(name, value)
+        self.setattr(name, value)
 
     def _setattr(self, name, value, force_permissive=False, not_raises=False):
+        """use setattr instead of _setattr
+        """
+        self.setattr(name, value, force_permissive=force_permissive,
+                     not_raises=not_raises)
+
+    def setattr(self, name, value, force_permissive=False, not_raises=False):
         if name.startswith('_impl_'):
             object.__setattr__(self, name, value)
             return
         if '.' in name:  # pragma: optional cover
             homeconfig, name = self.cfgimpl_get_home_by_path(name)
-            return homeconfig._setattr(name, value, force_permissive,
-                                       not_raises)
+            return homeconfig.setattr(name, value, force_permissive,
+                                      not_raises)
         context = self._cfgimpl_get_context()
         child = self.cfgimpl_get_description().__getattr__(name,
                                                            context=context)
@@ -218,7 +224,7 @@ class SubConfig(object):
                 not isinstance(child, DynSymLinkOption):  # pragma: no dynoptiondescription cover
             path = context.cfgimpl_get_description().impl_get_path_by_opt(
                 child._impl_getopt())
-            context._setattr(path, value, force_permissive, not_raises)
+            context.setattr(path, value, force_permissive, not_raises)
         else:
             subpath = self._get_subpath(name)
             self.cfgimpl_get_values().setitem(child, value, subpath,
@@ -756,7 +762,7 @@ class GroupConfig(_CommonConfig):
             elif isinstance(child, GroupConfig):
                 child.set_value(path, value)
             else:
-                child._setattr(path, value, not_raises=True)
+                child.setattr(path, value, not_raises=True)
 
     def find_firsts(self, byname=None, bypath=undefined, byoption=undefined,
                     byvalue=undefined, raise_if_not_found=True, _sub=False,