1 stable release
1.0.0 | Aug 7, 2024 |
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#31 in #derive-error
10KB
and-then-map-err
Provides traits for chaining Result
operations with different error types WITHOUT the need for intermediate map_err
calls.
lib.rs
:
and_then_map_err
and_then_map_err
provides traits for chaining Result
operations
with different error types without needing intermediate map_err
calls.
This allows more flexible error handling by converting error types
between chained operations.
Features
AndThenMapErr
trait: Enables chainingResult
operations where the error type can be converted.MapErrAndThen
trait: Enables mapping the error type of initialResult
before chaining another operation.
Examples
use thiserror::Error;
use and_then_map_err::{AndThenMapErr, MapErrAndThen};
#[derive(Error, Debug, Eq, PartialEq)]
pub enum ParentError {
#[error("parent error: {0}")]
Parent(String),
#[error("parent error from child error: {0}")]
FromChild(#[from] ChildError),
}
#[derive(Error, Debug, Eq, PartialEq)]
pub enum ChildError {
#[error("child error: {0}")]
Child(String),
}
let result_or_parent_err: Result<(), ParentError> = Ok(());
let new_result_or_parent_err: Result<(), ParentError> = result_or_parent_err.and_then_map_err(|x| {
Err(ChildError::Child("error occurred afterwards".to_string()))
});
assert_eq!(new_result_or_parent_err, Err(ParentError::FromChild(ChildError::Child("error occurred afterwards".to_string()))));
let result_or_child_err: Result<(), ChildError> = Err(ChildError::Child("initial error".to_string()));
let new_result_or_parent_err: Result<(), ParentError> = result_or_child_err.map_err_and_then(|x| {
Ok(x)
});
assert_eq!(new_result_or_parent_err, Err(ParentError::FromChild(ChildError::Child("initial error".to_string()))));