PyO3 将 TryFrom 错误转换为 PyErr-解网

问：

我正在尝试为一些 Rust 代码编写一个 Python 包装器，它在内部进行一些转换：TryFrom

pub enum MicrophoneType {
    Bidirectional,
    Omnidirectional,
}

impl TryFrom<char> for MicrophoneType {
    type Error = &'static str;

    fn try_from(x: char) -> Result<Self, Self::Error> {
        match x {
            'b' => Ok(Self::Bidirectional),
            'o' => Ok(Self::Omnidirectional),
            _ => Err("MicrophoneType: Invalid character given"),
        }
    }
}

#[pyfunction]
fn compute(
    _py: Python,
    microphone: char,
) -> PyResult<()> {
    let _microphone = MicrophoneType::try_from(microphone)?;

    Ok(())
}

但是，我看到错误消息

error[E0277]: `?` couldn't convert the error to `PyErr`
  --> rir_generator_py/src/lib.rs:59:59
   |
58 | ) -> PyResult<()> {
   |      ------------ expected `PyErr` because of this
59 |     let _microphone = MicrophoneType::try_from(microphone)?;
   |                                                           ^ the trait `From<&str>` is not implemented for `PyErr`

我对为什么感到困惑。

看来PyO3不知道如何处理我的类型，对吧？但这难道不是给出错误消息的默认方式吗？如果 PyO3 是一种常见模式，难道不应该期待这些吗？我在这里错过了什么？type Error = &'static str;impl

锈 PYO3型

#[derive(Debug)]
pub struct InvalidMicrophoneCharError {}

impl Error for InvalidMicrophoneCharError {}

impl fmt::Display for InvalidMicrophoneCharError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Incorrect microphone character")
    }
}

impl TryFrom<char> for MicrophoneType {
    type Error = InvalidMicrophoneCharError;

    fn try_from(x: char) -> Result<Self, Self::Error> {
        match x {
            'b' => Ok(Self::Bidirectional),
            'o' => Ok(Self::Omnidirectional),
            _ => Err(InvalidMicrophoneCharError {}),
        }
    }
}

其次，你必须使用 newtype 模式创建一个 “-chain”，它以 your type 开头，以 a 结尾，然后可以与 PyO3 对 Rust 原生 s 的支持相结合：FromPyErrResult<T, E>

struct MyInvalidMicrophoneCharError(InvalidMicrophoneCharError);

impl From<MyInvalidMicrophoneCharError> for PyErr {
    fn from(err: MyInvalidMicrophoneCharError) -> Self {
        PyValueError::new_err(err.0.to_string())
    }
}

impl From<InvalidMicrophoneCharError> for MyInvalidMicrophoneCharError {
    fn from(other: InvalidMicrophoneCharError) -> Self {
        Self(other)
    }
}

#[pyfunction]
fn compute(
    _py: Python,
    microphone: char,
) -> Result<(), MyInvalidMicrophoneCharError> {
    let _microphone = MicrophoneType::try_from(microphone)?;

    Ok(())
}

或者跳过链条，直接使用map_err()

#[pyfunction]
fn compute(
    _py: Python,
    microphone: char,
) -> Result<(), MyInvalidMicrophoneCharError> {
    let _microphone = MicrophoneType::try_from(microphone)
        .map_err(|error| PyValueError::new_err(error.to_string()))?;

    Ok(())
}

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PyO3 将 TryFrom 错误转换为 PyErr

PyO3 turn TryFrom errors into PyErr

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