diff --git a/tiramisu/setting.py b/tiramisu/setting.py
index 15b4c2a..71a076b 100644
--- a/tiramisu/setting.py
+++ b/tiramisu/setting.py
@@ -586,41 +586,49 @@ class Settings(object):
     # validate properties
 
     def validate_properties(self,
-                            opt_or_descr,
+                            opt,
                             path,
                             setting_properties,
                             index=None,
                             force_permissive=False):
         """
-        validation upon the properties related to `opt_or_descr`
+        validation upon the properties related to `opt`
 
-        :param opt_or_descr: an option or an option description object
+        :param opt: an option or an option description object
         :param force_permissive: behaves as if the permissive property
                                  was present
         """
         # opt properties
-        properties = self.getproperties(opt_or_descr,
-                                        path,
-                                        setting_properties=setting_properties,
-                                        index=index)
+        self_properties = self.getproperties(opt,
+                                             path,
+                                             setting_properties=setting_properties,
+                                             index=index)
+
         # calc properties
-        properties &= setting_properties - set(['frozen'])
-        if not opt_or_descr.impl_is_optiondescription():
+        properties = self_properties & setting_properties - set(['frozen'])
+        if not opt.impl_is_optiondescription():
             #mandatory
             if 'mandatory' in properties or 'empty' in properties:
-                value = 'pouet'
-                if self.validate_mandatory(opt_or_descr,
-                                           index,
-                                           value,
-                                           setting_properties,
-                                           properties):
-                    properties += set(['mandatory']) - set(['empty'])
+                value = self._getcontext().cfgimpl_get_values().get_cached_value(opt,
+                                                                                 path=path,
+                                                                                 validate=False,
+                                                                                 setting_properties=setting_properties,
+                                                                                 self_properties=self_properties,
+                                                                                 index=index)
+                if not self.validate_mandatory(opt,
+                                               index,
+                                               value,
+                                               setting_properties,
+                                               properties):
+                    properties -= set(['mandatory'])
                 else:
-                    properties -= set(['mandatory', 'empty'])
+                    properties |= set(['mandatory'])
+                properties -= set(['empty'])
             opt_type = 'option'
         else:
             opt_type = 'optiondescription'
 
+
         # remove permissive properties
         if force_permissive is True and properties:
             # remove global permissive if need
@@ -628,7 +636,7 @@ class Settings(object):
 
         # at this point an option should not remain in properties
         if properties != frozenset():
-            datas = {'opt': opt_or_descr,
+            datas = {'opt': opt,
                      'path': path,
                      'setting_properties': setting_properties,
                      'index': index,
diff --git a/tiramisu/value.py b/tiramisu/value.py
index 07ce96b..02ee9d6 100644
--- a/tiramisu/value.py
+++ b/tiramisu/value.py
@@ -70,16 +70,7 @@ class Values(object):
                          self_properties=undefined,
                          index=None,
                          display_warnings=True):
-        context = self._getcontext()
-        settings = context.cfgimpl_get_settings()
-        if path is None:
-            path = opt.impl_getpath(context)
         ntime = None
-        if self_properties is undefined:
-            self_properties = settings.getproperties(opt,
-                                                     path,
-                                                     setting_properties=setting_properties,
-                                                     index=index)
         if 'cache' in setting_properties and self._p_.hascache(path, index):
             if 'expire' in setting_properties:
                 ntime = int(time())
@@ -113,7 +104,7 @@ class Values(object):
                             path,
                             validate,
                             setting_properties,
-                            self_properties=None,
+                            self_properties=undefined,
                             index=None,
                             display_warnings=True,
                             force_permissive=False):
@@ -181,6 +172,12 @@ class Values(object):
         :param opt: the `option.Option()` object
         :returns: the option's value (or the default value if not set)
         """
+        if self_properties is undefined:
+            settings = self._getcontext().cfgimpl_get_settings()
+            self_properties = settings.getproperties(opt,
+                                                     path,
+                                                     setting_properties=setting_properties,
+                                                     index=index)
         force_default = 'frozen' in self_properties and \
             'force_default_on_freeze' in self_properties
         # not default value
@@ -243,9 +240,13 @@ class Values(object):
             context.cfgimpl_reset_cache(opt=opt,
                                         path=path)
 
+        if opt.impl_is_master_slaves('slave'):
+            index_ = index
+        else:
+            index_ = None
         if self._is_meta(opt,
                          path,
-                         index,
+                         index_,
                          setting_properties,
                          force_permissive=force_permissive):
             meta = context.cfgimpl_get_meta()
@@ -344,10 +345,7 @@ class Values(object):
                 else:
                     allow_empty_list = opt.impl_allow_empty_list()
                     if allow_empty_list is undefined:
-                        if opt.impl_is_master_slaves('slave'):
-                            allow_empty_list = True
-                        else:
-                            allow_empty_list = False
+                        allow_empty_list = opt.impl_is_master_slaves('slave')
                 isempty = value is None or (not allow_empty_list and value == []) or \
                     None in value or empty in value
             else:
@@ -744,7 +742,8 @@ class Values(object):
     #______________________________________________________________________
     # mandatory warnings
 
-    def mandatory_warnings(self, force_permissive=True):
+    def mandatory_warnings(self,
+                           force_permissive=True):
         """convenience function to trace Options that are mandatory and
         where no value has been set
 
@@ -776,10 +775,14 @@ class Values(object):
 
                 if opt.impl_is_optiondescription():
                     #FIXME ?
-                    if not settings.validate_properties(opt, True, False, path=path,
+                    if not settings.validate_properties(opt,
+                                                        True,
+                                                        False,
+                                                        path=path,
                                                         force_permissive=True,
                                                         setting_properties=setting_properties):
-                        for path in _mandatory_warnings(opt, currpath + [name]):
+                        for path in _mandatory_warnings(opt,
+                                                        currpath + [name]):
                             yield path
                 else:
                     if opt.impl_is_symlinkoption():
@@ -788,7 +791,8 @@ class Values(object):
                                                              path,
                                                              setting_properties=setting_properties)
                     if 'mandatory' in self_properties or 'empty' in self_properties:
-                        err = self.get_cached_value(opt, path=path,
+                        err = self.get_cached_value(opt,
+                                                    path=path,
                                                     trusted_cached_properties=False,
                                                     force_permissive=True,
                                                     setting_properties=setting_properties,