获取类属性的属性名称

Question

这是两个离散的对象:

class Field(object):
    pass

class MyClass(object):
    spam = Field()
    eggs = Field()
    potato = Field()

对于任何Field对象,是否存在一种方法让该对象知道MyClass分配它的属性名称？

我知道我可以将参数传递给Field对象,potato = Field(name='potato')但是在我的实际情况下这将是混乱和繁琐的,所以我只是想知道是否有非手动方式做同样的事情.

谢谢!

Answer 1

是的,您可以使Field类成为描述符,然后使用__set_name__方法绑定名称.无需特殊处理MyClass.

object.__set_name__(self, owner, name) 在创建拥有类所有者时调用.描述符已分配给name.

此方法适用于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'