Python 描述符 data 和 non-data 兩種類型

標籤：

僅包含__get__的,是non-data descriptor, 如果執行個體__dict__包含同名變數, 則執行個體優先; 如果還包含__set__, 則是data descriptor, 優先於執行個體__dict__同名變數.

class c:    passclass a:    def __init__(self, name):        self.name = name    def __get__(self, ins, cls):        print(‘call %s get: ‘%type(self).__name__, end=‘‘)        ins.__dict__[self.name] = c()        return ins.__dict__[self.name]class a2(a):    def __set__(self, ins, val):        ins.__dict__[self.name] = val    class t:    x=a(‘x‘)    y=a2(‘y‘)b = t()print(b.x)print(b.x)print(b.y)print(b.y)

 

結果:

>>> call a get: <__main__.c object at 0x0000000002A47B00><__main__.c object at 0x0000000002A47B00>call a2 get: <__main__.c object at 0x0000000002B27208>call a2 get: <__main__.c object at 0x0000000002B27278>

 

Python 描述符 data 和 non-data 兩種類型