Exception that calls `super().__init__` breaks `copy.copy`
还没有人认领这个 Issue。
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- Python
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描述
Bug report
Bug description:
For some reason calling Exception.__init__ breaks copy.copys ability to detect args. The following code
import copy
class MyException(Exception):
def __init__(self, x):
super().__init__()
self.x = x
my_exc = MyException(5)
copy.copy(my_exc)
gives
Traceback (most recent call last):
File "./foo.py", line 9, in <module>
copy.copy(my_exc)
File "/usr/lib/python3.12/copy.py", line 97, in copy
return _reconstruct(x, None, *rv)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/copy.py", line 253, in _reconstruct
y = func(*args)
^^^^^^^^^^^
TypeError: MyException.__init__() missing 1 required positional argument: 'x'
Removing the super().__init__() line makes everything work as expected, but given that it's generally seen as good practice to call super().__init__() in child classes, and you may be working with a more complex class structure, this seems like pretty bad behavior.
I haven't dug deep enough into copy.copy or BaseException.__init__ to decide which one deserves the blame.
For the reason why I want to copy exceptions, see https://github.com/python-trio/flake8-async/issues/298
CPython versions tested on:
3.9, 3.10, 3.11, 3.12, 3.13, 3.14
Operating systems tested on:
Linux
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调研方向
使用 copy.copy 重现该示例,并结合 BaseException.init 检查 /usr/lib/python3.12/copy.py 中的行为。确定初始化器调用 super().init() 的 Exception 的预期复制行为,然后添加一个回归测试,表明复制能够保留所需的构造函数状态且不会引发 TypeError。
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评估
- 技术栈
- python
- 领域
- backend
- Issue 类型
- 缺陷
- 难度
- 4/5
- 预计耗时
- 3-5 天
- 活跃度
- 停滞
- 描述清晰度
- 基本清楚
- 新手友好度
- 35/100