property实现原理

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.")
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__)