Expand description
§derive_enum_error
§Deriving error sources
Add an #[error(source)]
attribute to the field:
use derive_enum_error::Error;
use std::io;
/// `MyError::source` will return a reference to the `io_error` field
#[derive(Debug, Error)]
#[error(display = "An error occurred.")]
struct MyError {
#[error(source)]
io_error: io::Error,
}
§Formatting fields
use derive_enum_error::Error;
use std::path::PathBuf;
#[derive(Debug, Error)]
pub enum FormatError {
#[error(display = "invalid header (expected: {:?}, got: {:?})", expected, found)]
InvalidHeader {
expected: String,
found: String,
},
// Note that tuple fields need to be prefixed with `_`
#[error(display = "missing attribute: {:?}", _0)]
MissingAttribute(String),
}
#[derive(Debug, Error)]
pub enum LoadingError {
#[error(display = "could not decode file")]
FormatError(#[error(source)] FormatError),
#[error(display = "could not find file: {:?}", path)]
NotFound { path: PathBuf },
}
§Printing the error
use std::error::Error;
fn print_error(e: &dyn Error) {
eprintln!("error: {}", e);
let mut source = e.source();
while let Some(e) = source {
eprintln!("sourced by: {}", e);
source = e.source();
}
}