Merge pull request #1679 from messense/error-cause

Add support for setting and retrieving exception cause
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David Hewitt 2021-06-24 07:58:34 +01:00 committed by GitHub
commit a02353ce34
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2 changed files with 55 additions and 0 deletions

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@ -31,6 +31,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
- Add support for `#[pyclass(extends=Exception)]`. [#1591](https://github.com/PyO3/pyo3/pull/1591)
- Add support for extracting `PathBuf` from `pathlib.Path`. [#1654](https://github.com/PyO3/pyo3/pull/1654)
- Add `#[pyo3(text_signature = "...")]` syntax for setting text signature. [#1658](https://github.com/PyO3/pyo3/pull/1658)
- Add support for setting and retrieving exception cause. [#1679](https://github.com/PyO3/pyo3/pull/1679)
### Changed

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@ -390,6 +390,28 @@ impl PyErr {
PyErr::from_state(PyErrState::Normalized(self.normalized(py).clone()))
}
/// Return the cause (either an exception instance, or None, set by `raise ... from ...`)
/// associated with the exception, as accessible from Python through `__cause__`.
pub fn cause(&self, py: Python) -> Option<PyErr> {
let ptr = unsafe { ffi::PyException_GetCause(self.pvalue(py).as_ptr()) };
let obj = unsafe { py.from_owned_ptr_or_opt::<PyAny>(ptr) };
obj.map(|x| Self::from_instance(x))
}
/// Set the cause associated with the exception, pass `None` to clear it.
pub fn set_cause(&self, py: Python, cause: Option<Self>) {
if let Some(cause) = cause {
let cause = cause.into_instance(py);
unsafe {
ffi::PyException_SetCause(self.pvalue(py).as_ptr(), cause.as_ptr());
}
} else {
unsafe {
ffi::PyException_SetCause(self.pvalue(py).as_ptr(), std::ptr::null_mut());
}
}
}
fn from_state(state: PyErrState) -> PyErr {
PyErr {
state: UnsafeCell::new(Some(state)),
@ -627,4 +649,36 @@ mod tests {
is_send::<PyErrState>();
is_sync::<PyErrState>();
}
#[test]
fn test_pyerr_cause() {
Python::with_gil(|py| {
let err = py
.run("raise Exception('banana')", None, None)
.expect_err("raising should have given us an error");
assert!(err.cause(py).is_none());
let err = py
.run(
"raise Exception('banana') from Exception('apple')",
None,
None,
)
.expect_err("raising should have given us an error");
let cause = err
.cause(py)
.expect("raising from should have given us a cause");
assert_eq!(cause.to_string(), "Exception: apple");
err.set_cause(py, None);
assert!(err.cause(py).is_none());
let new_cause = exceptions::PyValueError::new_err("orange");
err.set_cause(py, Some(new_cause));
let cause = err
.cause(py)
.expect("set_cause should have given us a cause");
assert_eq!(cause.to_string(), "ValueError: orange");
});
}
}