Example of code reduction with thiserror

error_example_thiserror.rs

// These are equivalent: manual `ServerError` impls vs. `thiserror`'s derive macros.

#[derive(Debug)]
enum ServerError {
    Io(std::io::Error),
    Oxen(OxenError),
}

impl std::error::Error for ServerError {}

impl From<std::io::Error> for ServerError {
    fn from(err: std::io::Error) -> Self {
        ServerError::Io(err)
    }
}

impl From<OxenError> for ServerError {
    fn from(err: OxenError) -> Self {
        ServerError::Oxen(err)
    }
}

impl std::fmt::Display for ServerError {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        match self {
            Self::Io(err) => write!(f, "{}", err),
            Self::Oxen(err) => write!(f, "{}", err),
        }
    }
}


////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////

#[derive(Debug, Error)]
enum ServerError {
    #[error("{0}")]
    Io(#[from] std::io::Error),
    #[error("{0}")]
    Oxen(#[from] OxenError),
}