Skip to content
GitHub no longer supports this web browser. Learn more about the browsers we support.
Rust doesn't have exceptions
Rust
Branch: master
Clone or download
boats
boats Merge pull request #23 from tversteeg/patch-1
Add documentation badge to README.md
Latest commit af4f6b8 Nov 21, 2019

README.md

Der Fehler

Documentation

Der Fehler is a library to add support for "throwing functions" to Rust through procedural macros. Functions marked with the throws attribute return Result, but the "Ok" path is used by default and you don't need to wrap ok return values in Ok. To throw errors, use ? or the throws macro.

Der Fehler provides these items:

The #[throws] attribute

The throws attribute modifies a function or method to make it return a Result. It takes an optional typename as an argument to the attribute which will be the error type of this function; if no typename is supplied, it uses the default error type for this crate.

Within the function body, returns (including the implicit final return) are automatically "Ok-wrapped." To raise errors, use ? or the throws! macro.

For example, these two functions are equivalent:

#[throws(i32)]
fn foo(x: bool) -> i32 {
    if x {
        0
    } else {
        throw!(1);
    }
}

fn bar(x: bool) -> Result<i32, i32> {
    if x {
        Ok(0)
    } else {
        Err(1)
    }
}

The throw! macro

throw! is a macro which is equivalent to the Err($e)? pattern. It takes an error type and "throws" it.

One important aspect of the throw! macro is that it allows you to return errors inside of functions marked with throws. You cannot just return errors from these functions, you need to use this macro.

TODO

  • Make throws work on closures and async blocks (attributes are not allowed on expressions on stable)

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

You can’t perform that action at this time.