#error #result #utility #error-handling

no-std utils-results

The easiest and most intuitive error handling solution

17 stable releases (4 major)

5.3.0 Oct 18, 2021
5.2.1 Sep 2, 2021
5.1.1 Aug 28, 2021
4.3.1 Aug 10, 2021
1.1.2 Jul 29, 2021

#1385 in Rust patterns

44 downloads per month
Used in 3 crates

MIT/Apache

25KB
207 lines

utils-results

The easiest and most intuitive error handling solution.

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| Docs | Latest Note |

[dependencies]
utils_results = "5.3.0"

No-std

Disable default feature(allocator is needed).

[dependencies]
utils_results = { version = "5.3.0", default-features = false }

Overview

First, You should make your own an error set.

err! {
     BrokenHeader => "broken header."
     AnotherHeader => "not matched header."
     FileNotFound => "file not found."
     EmptyArgument => "empty argument."
     UnexpectedEof => "unexpected eof."
     OutOfBounds => "index out of bounds."
     NotMatched => "btw not matched."
}

And just errbang!

errbang!(err::BrokenHeader)

More Examples

fn foo() -> Result<bool> { // Our Master Result Type
    let bar = 2;
    match bar {
        0 => Ok(true),
        1 => Ok(false),
        _ => errbang!(err::NotMatched, "{} is {}", "bar", bar),
    }
}


fn main() -> Result<()> {
    let _is_bar_zero = foo()?;
    Ok(())
}
errbang!("error.");
errbang!(err::MyError1);
errbang!(err::MyError2, "cannot find.");
errbang!(err::MyError3, "{} is {}", "bar", 2);

| Result

[src/main.rs 40:1] unexpected eof. bar is 2 <err::UnexpectedEof>

unwrapping error input data. also can easily compare them.

fn foo() -> Result<()> {
    // example
    return errbang!(err::Bar, "this is input.");
}

assert_eq!(
   errunwrap!(foo(), err::Bar), "this is input."
);

Important

    1. One result type(anyhow).
    1. All casted errors have their own chaining error' information(all the previous errors).

if you follow below rules, you can easily debug all your projects.

errbang -> errcast -> errcast -> ... -> errcast -> errextract


* Quick Overview

use utils_results::*;

err! {
    One => "this error is first one."
    Two => "this error is second one."
    Three => "this error is third one."
    Well => "is this?"
}


fn aaa() -> Result<usize> {
    return errbang!(err::One, "{}.error bang!", 1);
}

fn bbb() -> Result<usize> {
    let n = errcast!(aaa(), err::Two, "{}.two <- one.", 2);
    Ok(n)
}

fn ccc() -> Result<usize> {
    Ok(errcast!(bbb(), err::Three, "{}.three <- two.", 3))
}


fn main() -> Result<()> {
    let c = errextract!(ccc(), err::Well => 127);
    eprintln!("1/{} is cosmological constant.", c);
    Ok(())
}

| Result

Error:


  [src/main.rs 11:12] this error is first one. 1.error bang! <err::One> aaa()
                     ⎺↴
  [src/main.rs 14:13] this error is second one. 2.two <- one. <err::Two> bbb()
                     ⎺↴
  [src/main.rs 18:8] this error is third one. 3.three <- two. <err::Three>


If the matching error has changed,

// Well to Three
let c = errextract!(ccc(), err::Three => 127);

| Result

1/127 is cosmological constant.

errcast

Any type of error can be converted into our Master Error. (non panic unwraping)

<Unwraped Ok> = errcast! (<Any Result>, <Master Err>, <Optional meta,..>);
// example
let num_read = errcast!(file.read(&mut buf), err::ReadErr, "this is {} data.", "meta");

Simply just do this!

let file = errcast!(File::open("test"), err::FileOpenError)

or...

// Master `Result` can take any errors
let file = File::open("test")?;

// if cfg!(no_std),
let file = io_to_err!(File::open("test"))?;

But, errcast -> errextract combo is always good choice.

fn exe(path: &str) -> Result<usize> {
    let file = errcast!(File::open("test"), err::FileOpenError);
    // .....
    // ...
    Ok(num)
}

fn main() -> Result<()> {
    /// non panic unwraping
    /// and specific error can return
    /// matching block
    let num = errextract!(exe(path),
        err::FileOpenError => 0);
    /// other errors will go out -> Result<T>

    Ok(())
}

Well, we can also handle io::Error more idiomatic way. (feature = "std")

Matching io::Error


 io_err! {
     // io::ErrorKind => err::MyError
     UnexpectedEof => err::MyError1
     Interrupted => err::MyError2
     NotFound => err::MyError3
     // ...
 }

Declare matching macro and just handle that.


io_to_err!(file.seek(SeekFrom::End(0)))?;

err_to_io!(my_seek(0))?;


Master Result

  • Please use our Master Result<T>
    instead std::result::Result or io::Result etc..
  • this is anyhow Result.

utils-results/lib.rs Definition
/// Master Result
pub type Result<T> = anyhow::Result<T>;

just put this in your project.

pub use utils_results::*;

You can also convert any type of Result

// to our Master Result
resultcast!(handle.join().unwrap())?;

Dependencies

~130KB