python - 获取类属性的属性名

Question

这里有两个离散的对象:

class Field(object):
    pass

class MyClass(object):
    firstname = Field()
    lastname = Field()
    email = Field()

对于任何 Field 对象，是否有一种固有的方式让该对象知道 MyClass 分配给它的属性名称？

我知道我可以将参数传递给 Field 对象，例如 email = Field(name='email')，但在我的实际工作中这会很困惑和乏味情况，所以我只是想知道是否有一种非手动的方式来做同样的事情。

谢谢!

Answer 1

是的，您可以将 Field 类设为 descriptor , 然后使用 __set_name__绑定(bind)名称的方法。 MyClass 中不需要特殊处理。

object.__set_name__(self, owner, name) Called at the time the owning class owner is created. The descriptor has been assigned to name.

这个方法是available in Python 3.6+ .

>>> class Field:
...     def __set_name__(self, owner, name):
...         print('__set_name__ was called!')
...         print(f'self: {self!r}')  # this is the Field instance (descriptor)
...         print(f'owner: {owner!r}')  # this is the owning class (e.g. MyClass) 
...         print(f'name: {name!r}')  # the name the descriptor was bound to
... 
>>> class MyClass:
...     potato = Field()
... 
__set_name__ was called!
self: <__main__.Field object at 0xcafef00d>
owner: <class '__main__.MyClass'>
name: 'potato'