def __setattr__(self, key, value):
""" After owner is set disallow any field assignment """
if getattr(self, 'owner', None) is not None:
raise TraitAttributeError(
"Can't change an Attr after it has been bound to a class."
"Reusing Attr instances for different fields is not supported."
)
super(_Attr, self).__setattr__(key, value)
def __set__(self, instance, value):
if isinstance(value, str):
try:
value = uuid.UUID(value)
except ValueError:
raise TraitAttributeError("Given value cannot be used as UUID for field {}".format(self.field_name))
super(DataTypeGidAttr, self).__set__(instance, value)
def __delete__(self, instance):
raise TraitAttributeError("can't be deleted", attr=self)
def __delattr__(self, item):
raise TraitAttributeError("Deleting an Attr field is not supported.")