def _del(self, obj, value=None):
old = self._get(obj)
try:
delattr(obj, self._name)
except AttributeError:
pass
else:
self.handle(AttributeChangeEvent(obj, self, old, self.default))
def _set(self, obj, value):
if not value in self.values:
raise AttributeError("Value should be one of %s" % str(self.values))
old = self._get(obj)
if value == old:
return
if value == self.default:
delattr(obj, self._name)
else:
setattr(obj, self._name, value)
self.handle(AttributeChangeEvent(obj, self, old, value))
def _set(self, obj, value):
if value is not None:
if not isinstance(value, self.type) and not isinstance(value, str):
raise AttributeError(
"Value should be of type %s" % hasattr(self.type, "__name__")
and self.type.__name__
or self.type
)
if value == self._get(obj):
return
old = self._get(obj)
if value == self.default and hasattr(obj, self._name):
delattr(obj, self._name)
else:
setattr(obj, self._name, value)
self.handle(AttributeChangeEvent(obj, self, old, value))