在派生类上调用 coerce() 方法会导致错误

发布于 2024-10-16 03:28:26 字数 722 浏览 6 评论 0原文

我的试验如下，但没有成功。

class MyNum:
   def __init__(self , n):
   self.n = n

class MyNum2(MyNum):
   def __coerce__(self , y):
        return self, y

   def __radd__(self, y):
        print 'radd called'
        return self.n + y.n

我在 python 命令行中输入：

>>> x = MyNum(20)
>>> y = MyNum2(12)
>>> x+y

结果：

>>> Traceback (most recent call last):
  File "", line 1, in 
    y+x
  File "", line 3, in __coerce__
    return self.y
AttributeError: MyNum instance has no attribute 'y'

当我使用 __coerce__() 方法而不进行类派生时，结果为 x+y 等于 radd 调用 // 32。但是，对于派生类，会发生错误。

请给我一些帮助，祝农历新年快乐，提前谢谢。

原文

My trial was like below, but it didn't work.

class MyNum:
   def __init__(self , n):
   self.n = n

class MyNum2(MyNum):
   def __coerce__(self , y):
        return self, y

   def __radd__(self, y):
        print 'radd called'
        return self.n + y.n

I typed on the python command line:

>>> x = MyNum(20)
>>> y = MyNum2(12)
>>> x+y

Result:

>>> Traceback (most recent call last):
  File "", line 1, in 
    y+x
  File "", line 3, in __coerce__
    return self.y
AttributeError: MyNum instance has no attribute 'y'

When I use the __coerce__() method without class deriving, the result of
x+y equals to radd called // 32. However, with derived-class, an error occurs.

Please give me some help, and happy lunar new year, thank you in advance.

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纵山崖 2024-10-23 03:28:26

根据错误消息，您的 __coerce__ 实现实际上具有

return self.y

而不是

return self,y

您在示例代码中编写的内容。

上面的代码对我有用，实际上您甚至不需要这里的 __coerce__ 方法。在您的示例中，只需使用 __radd__ 就足够了。

Based on the error message, your __coerce__ implementation actually had

return self.y

instead of the

return self,y

as you've written in the example code.

Your code above works for me, and you don't actually even need the __coerce__ method here. Just having the __radd__ is sufficient in your example.

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