Expose exception cause as std::nested_exception #4033
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Skylion007
reviewed
Jun 29, 2022
| if (not cause or cause.is_none()) | ||
| return std::nested_exception(); | ||
| auto typ = type::of(cause); | ||
| auto tb = reinterpret_steal<object>(PyException_GetTraceback(cause.ptr())); |
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PyException_GetTraceback can return null. Will PyErr_Restore work if this is the case?
Skylion007
reviewed
Jun 29, 2022
| auto tb = reinterpret_steal<object>(PyException_GetTraceback(cause.ptr())); | ||
| PyErr_Restore(typ.release().ptr(), cause.release().ptr(), tb.release().ptr()); | ||
| try { | ||
| throw error_already_set(); |
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Throwing is very slow and something that is best avoided here. is there a way we avoid having to throw the exception just to catch and return an empty std::nested_exception?
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Can't we just use the CPython API to check if the exception is nested instead?
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Description
Expose Python exception cause (
raise ... from ...) to C++ viastd::nested_exception. Inverse of #3608.Useful after #3605 etc.
Does not set std::nested_exception base if a C++ exception is already present, for backwards compatibility if anyone is already using
std::throw_with_nested(py::error_already_set()).Suggested changelog entry: