better raise message if try to launch impl_get_information/impl_set_information in uncompatible class

tiramisu/option.py

@@ -64,19 +64,27 @@ class BaseInformation(object):
         :param key: information's key (ex: "help", "doc"
         :param value: information's value (ex: "the help string")
         """
+        try:
             self._impl_informations[key] = value
+        except AttributeError:
+            raise AttributeError(_('{0} instance has no attribute '
+                                   'impl_set_information').format(self.__class__.__name__))
 
     def impl_get_information(self, key, default=None):
         """retrieves one information's item
 
         :param key: the item string (ex: "help")
         """
+        try:
             if key in self._impl_informations:
                 return self._impl_informations[key]
             elif default is not None:
                 return default
             else:
                 raise ValueError(_("Information's item not found: {0}").format(key))
+        except AttributeError:
+            raise AttributeError(_('{0} instance has no attribute '
+                                   'impl_get_information').format(self.__class__.__name__))
 
 
 class Option(BaseInformation):