9 releases (2 stable)
1.0.1 | Oct 23, 2020 |
---|---|
1.0.0 | Nov 11, 2019 |
0.2.5 | Jun 18, 2019 |
0.2.1 | May 31, 2019 |
0.1.3 | May 27, 2019 |
#5 in #archived
27 downloads per month
Used in plotly-types
17KB
228 lines
error-rules
Archived
Project archived. I recommend to use anyhow + thiserror.
Intro
error-rules is a derive macro to implement error handler with a errors chaining. Macro automatically implements conversion of any error type into the inner enum field.
Error conversion
#[error_from]
attribute implements an automatically conversion from any error type.
Converted type should implements std::error::Error
interface.
use error_rules::*;
#[derive(Debug, Error)]
enum AppError {
#[error_from("App IO: {}", 0)]
Io(std::io::Error),
}
type Result<T> = std::result::Result<T, AppError>;
fn example() -> Result<()> {
let _file = std::fs::File::open("not-found.txt")?;
unreachable!()
}
let error = example().unwrap_err();
assert_eq!(error.to_string().as_str(),
"App IO: No such file or directory (os error 2)");
Custom error kind
#[error_kind]
attribute describes custom error kind.
Could be defined without fields or with fields tuple.
use error_rules::*;
#[derive(Debug, Error)]
enum AppError {
#[error_kind("App: error without arguments")]
E1,
#[error_kind("App: code:{} message:{}", 0, 1)]
E2(usize, String),
}
type Result<T> = std::result::Result<T, AppError>;
fn example_1() -> Result<()> {
Err(AppError::E1)
}
fn example_2() -> Result<()> {
Err(AppError::E2(404, "Not Found".to_owned()))
}
let error = example_1().unwrap_err();
assert_eq!(error.to_string().as_str(),
"App: error without arguments");
let error = example_2().unwrap_err();
assert_eq!(error.to_string().as_str(),
"App: code:404 message:Not Found");
Display attributes
#[error_from]
and #[error_kind]
contain list of attributes to display error.
First attribute should be literal string. Other attributes is a number of the
unnamed field in the tuple. Started from 0.
#[error_from]
could defined without attributes it's equal to #[error_from("{}", 0)]
Error prefix
#[error_prefix]
attribute should be defined before enum declaration and
appends prefix into error text.
use error_rules::*;
#[derive(Debug, Error)]
#[error_prefx = "App"]
enum AppError {
#[error_from]
Io(std::io::Error),
}
type Result<T> = std::result::Result<T, AppError>;
fn example() -> Result<()> {
let _file = std::fs::File::open("not-found.txt")?;
unreachable!()
}
let error = example().unwrap_err();
assert_eq!(error.to_string().as_str(),
"App: No such file or directory (os error 2)");
Error chain
By implementing error for nested modules the primary error handler returns full chain of the error.
use error_rules::*;
#[derive(Debug, Error)]
#[error_prefix = "Mod"]
enum ModError {
#[error_from]
Io(std::io::Error),
}
fn mod_example() -> Result<(), ModError> {
let _file = std::fs::File::open("not-found.txt")?;
unreachable!()
}
#[derive(Debug, Error)]
#[error_prefix = "App"]
enum AppError {
#[error_from]
Mod(ModError),
}
fn app_example() -> Result<(), AppError> {
mod_example()?;
unreachable!()
}
let error = app_example().unwrap_err();
assert_eq!(error.to_string().as_str(),
"App: Mod: No such file or directory (os error 2)");
Dependencies
~1.5MB
~35K SLoC