时间：2022-12-29 10:51:46 | 栏目：Python代码 | 点击：次
在没有@property修饰的情况下，需要分别声明get、set、delete函数，然后初始化property类，将这些方法加载进property中
class C持有property的实例化对象x
对外表现出来C().x时，实际上是调用C()中的x（property类）中设置的fset，fget，fdel，分别对应getx，setx，delx
C真正持有的x，是self._x被隐藏起来了
class C(object):
def getx(self):
return self._x
def setx(self, value):
self._x = value
def delx(self):
del self._x
x = property(getx, setx, delx, "I'm the 'x' property.")
property类 结合x = property(getx, setx, delx, "I'm the 'x' property.")与property的__init__()可以发现property接受四个参数
fget，用于获取属性值，
fset，用于设置属性值
fdel，用于删除属性
doc，属性的介绍
可以单独设置fget、fset、fdel…
x = property，x.getter(getx)，x.setter(setx)，x.deleter(delx)
class property(object):
def deleter(self, *args, **kwargs): # real signature unknown
""" Descriptor to change the deleter on a property. """
pass
def getter(self, *args, **kwargs): # real signature unknown
""" Descriptor to change the getter on a property. """
pass
def setter(self, *args, **kwargs): # real signature unknown
""" Descriptor to change the setter on a property. """
pass
def __delete__(self, *args, **kwargs): # real signature unknown
""" Delete an attribute of instance. """
pass
def __getattribute__(self, *args, **kwargs): # real signature unknown
""" Return getattr(self, name). """
pass
def __get__(self, *args, **kwargs): # real signature unknown
""" Return an attribute of instance, which is of type owner. """
pass
def __init__(self, fget=None, fset=None, fdel=None, doc=None): # known special case of
pass
需要注意，装饰器只是一个python的语法糖，可以拆解成普通使用方法，如property(getx)
@property创建了一个实例x，对于def x(self)实际上是C类持有x = property(fget=x)
因此，x.setter方法指向的是property.setter，也是起到装饰器效果x.setter(x)（注意，前者x是property实例x，后者x是def x(self, value)函数），x.deleter同理
class C(object):
@property
def x(self):
"I am the 'x' property."
return self._x
@x.setter
def x(self, value):
self._x = value
@x.deleter
def x(self):
del self._x
为什么property实例化后的名字与属性名一致？
换种问法就是为什么x = property(...)
可以认为是
attributes_and_methods = {
x.__name__: property(x), //声明C类持有property实例
#...
}
C = type('C', (object,), attributes_and_methods)
执行C().x时，调用的是C().x（property）绑定的fget方法，用过__get__唤醒，setter、deleter同理
class property(object):
#...
def __init__(self, fget=None, fset=None, fdel=None, doc=None):
self.fget = fget
self.fset = fset
self.fdel = fdel
...
def __get__(self, obj, objtype=None): # real signature unknown
if obj is None:
return self
if self.fget is None:
raise AttributeError("unreadable attribute")
return self.fget(obj)