fix: pickle exceptions with custom __reduce__ #2747
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srilman changed the title __reduce__ ![chatgpt-codex-connector[bot]](https://avatars.githubusercontent.com/in/1144995?s=60&v=4){kind=small}
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| @classmethod | ||
| def _reconstruct(cls, message: str, request: httpx.Request) -> Self: | ||
| return cls(message=message, request=request) | ||
| | ||
| @override | ||
| def __reduce__(self) -> tuple[Callable[..., Self], tuple[Any, ...]]: | ||
| return (self.__class__._reconstruct, (self.message, self.request)) |
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The new APIConnectionError.__reduce__ returns _reconstruct(self.message, self.request), which reconstructs the object via cls(message=message, request=request). APITimeoutError subclasses APIConnectionError but its __init__ takes only a request parameter and hard‑codes the message. Attempting to pickle an APITimeoutError will therefore raise TypeError: APITimeoutError.__init__() got an unexpected keyword argument 'message', defeating the goal of making these exceptions picklable. APITimeoutError needs its own __reduce__/reconstructor or _reconstruct must handle subclasses without a message parameter.
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Closes #2629. When working in a distributed environment, its useful to pickle and unpickle exceptions between workers. The default
__reduce__in Python does not account for keyword-only args, which is why we need to handle it ourselves.Alternatively, we could modify the constructor of the exception classes to not use keyword-only args, but that was a larger change.