我正在根据文档中的属性示例处理我自己的描述符:https ://docs.python.org/3/howto/descriptor.html#properties
但由于某种原因,我所有的属性都是一样的。
class Property(object):
"Emulate PyProperty_Type() in Objects/descrobject.c"
def __init__(self, fget=None, fset=None, fdel=None, doc=None):
self.fget = fget
self.fset = fset
self.fdel = fdel
if doc is None and fget is not None:
doc = fget.__doc__
self.__doc__ = doc
def __get__(self, obj, objtype=None):
if obj is None:
return self
if self.fget is None:
raise AttributeError("unreadable attribute")
return self.fget(obj)
def __set__(self, obj, value):
if self.fset is None:
raise AttributeError("can't set attribute")
self.fset(obj, value)
def __delete__(self, obj):
if self.fdel is None:
raise AttributeError("can't delete attribute")
self.fdel(obj)
def getter(self, fget):
return type(self)(fget, self.fset, self.fdel, self.__doc__)
def setter(self, fset):
return type(self)(self.fget, fset, self.fdel, self.__doc__)
def deleter(self, fdel):
return type(self)(self.fget, self.fset, fdel, self.__doc__)
class Demo(object):
def __init__(self, a=None, b=None):
self._a = a
self._b = b
@Property
def a(self):
return self._a
@a.setter
def a(self, a):
self._a = a
@Property
def b(self):
return self._b
@b.setter
def a(self, b):
self._b = b
d = Demo('4')
print(d.a, d.b) # None None (Should be: '4' None ?)
d.a = '3'
print(d.a, d.b) # 3 3 (Should be: '3' None ?)
首先,为什么传递给构造函数的值没有按我的意图设置/访问?为什么变化a
似乎b
也在变化?