class FamilyNameWithUnitsLinkage(HasTraits):
""" units and family_name are always compatible. family_name is the master
and must be changed first if you want to change both.
"""
family_name = FamilyNameTrait(
'length', is_strict=True, allow_none=False, units_trait='units')
units = UnitsTrait(
'm', is_strict=True, allow_none=False, family_trait='family_name')
def __init__(self, **traits):
""" Create a new FamilyNameWithUnitsLinkage. """
# HasTraits.__init__ will assign attributes from **traits in an abitrary
# order (its a dictionary). However, this class defines a relationship
# between units and family_name and therefore must make sure the
# assignments are done in the proper order.
if 'units' in traits and 'family_name' in traits:
units = traits.pop('units')
family_name = traits.pop('family_name')
else:
units = family_name = None
super(FamilyNameWithUnitsLinkage, self).__init__(**traits)
if units is not None:
self.family_name = family_name
self.units = units
return
class FamilyNameStrict(HasTraits):
family_name = FamilyNameTrait(is_strict=True)
class FamilyNameStrictNotNone(HasTraits):
family_name = FamilyNameTrait('unknown', is_strict=True, allow_none=False)
class UnitsStrictWithFamily(HasTraits):
units = UnitsTrait(
is_strict=True, allow_none=True, family_trait='family_name')
family_name = FamilyNameTrait('unknown', allow_none=False)