error-rules

Intro

error-rules is a derive macro to implement error handler based on the enum.

Implements next interfaces:

• std::fmt::Display for all enum variants
• std::error::Error and std::convert::From for source errors

Usage

```rust use std::io; use error_rules::*;

[derive(Debug, Error)]

enum HumanError { #[errorfrom("Human IO => {}", 0)] Io(io::Error), #[errorkind("Human => not found")] NotFound, }

[derive(Default)]

struct Human;

impl Human { pub fn invoke_failure(&self) -> Result<(), HumanError> { Err(io::Error::from(io::ErrorKind::PermissionDenied))?; unreachable!() } }

[derive(Debug, Error)]

enum BikeError { #[errorfrom("Bike IO => {}", 0)] Io(io::Error), #[errorfrom("Bike => {}", 0)] Human(HumanError), #[error_kind("Bike => speed limit")] SpeedLimit, }

[derive(Default)]

struct Bike(Human);

impl Bike { pub fn ride(&self) -> Result<(), BikeError> { self.0.invoke_failure()?; unreachable!() }

pub fn invoke_failure(&self) -> Result<(), BikeError> {
    Err(io::Error::from(io::ErrorKind::PermissionDenied))?;
    unreachable!()
}

}

let b = Bike::default();

let error = b.ride().unwraperr(); asserteq!(error.tostring().asstr(), "Bike => Human IO => permission denied");

let error = b.invokefailure().unwraperr(); asserteq!(error.tostring().as_str(), "Bike IO => permission denied"); ```

error_from

error_from attribute implements a converter from any error type into Error. Converted type should implements std::error::Error itnerface.

error_kind

error_kind attribute describes additional variant for Error. Could be defined without fields or with fields tuple

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.