remove option's storage

tiramisu/setting.py

@@ -114,6 +114,7 @@ log = getLogger('tiramisu')
 #import logging
 #logging.basicConfig(format='%(levelname)s:%(message)s', level=logging.DEBUG)
 debug = False
+static_set = frozenset()
 
 
 # ____________________________________________________________
@@ -261,7 +262,7 @@ class Property(object):
 
     def _append(self, propname, save=True):
         if self._opt is not None and self._opt.impl_getrequires() is not None \
-                and propname in self._opt.impl_get_calc_properties():  # pragma: optional cover
+                and propname in getattr(self._opt, '_calc_properties', static_set):  # pragma: optional cover
             raise ValueError(_('cannot append {0} property for option {1}: '
                                'this property is calculated').format(
                                    propname, self._opt.impl_getname()))