Announcing error-chain, a library for consistent and reliable Rust error handling

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error-chain 0.7.1 is out. This release reverts some changes from the 0.6 series that caused regressions in inference and usability. It also comes with a new bail! macro, syntax sugar for early return with type conversions.

The main things to be aware of compared to 0.6:

Declaring links { } again requires the ErrorKind name:

links {
    Utils(::utils::Error, ::utils::ErrorKind);
}

The ResultExt trait is once again defined by the error_chain! macro, not in the error_chain crate, and so must be mentioned in the types { } block:

types {
    Error, ErrorKind, ResultExt, Result;
}

The Error kind is again a tuple, not a struct, and is matched like a tuple:

match Error::from("error!") {
    Error(ErrorKind::InvalidToolchainName(_), _) => { }
    Error(ErrorKind::Msg(_), _) => { }
}

And the bail! macro:

fn foo() -> Result<()> {
    if bad_condition() {
        bail!(ErrorKind::FooError);
    }

    Ok(())
}

Which also works with fmt specifiers:

fn foo() -> Result<()> {
    if bad_condition() {
        bail!("bad stuff happened: {}", bad_stuff);
    }

    Ok(())
}

The bail! macro is inspired by a similar macro in Cargo and a similar throw construct in the exception handling RFC.

Finally, thanks to @Yamakaky for taking on some of the error-chain maintenance responsibilities in the last few weeks.

Contributors: Brian Anderson, Yamakaky

0.7.1

0.7.0

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