def __get__(self, instance, owner=None):
if instance is None:
return self
else:
try:
exp = self._instance_expressions[id(instance)]
except KeyError:
exp = coerce(self._factory(instance), size=self._size)
return _PropertyValue(self, instance, exp)
def __init__(self, size=1, make_default=None, *, name=None, doc=None):
self._instance_expressions = {}
if make_default:
self._size = size
self._factory = make_default
else:
self._size = size
default = coerce(0, size=size)
self._factory = lambda instance: default
self.name, component_names = _get_names(name, size)
self._component_names = {(i, i + 1): n
for i, n in enumerate(component_names)}
self.__doc__ = doc
def __set__(self, instance, value):
exp = self._vector_property.__get__(instance)
new = exp.replace(slice(self._start, self._end),
coerce(value, size=len(self)))
self._vector_property.__set__(instance, new)
def __set__(self, instance, value):
exp = coerce(value, size=self._size)
if id(instance) not in self._instance_expressions:
finalize(instance, self._instance_expressions.pop,
id(instance), None)
self._instance_expressions[id(instance)] = simplify(exp)
