Lib.rs

extension-eyre

Re-export of color-eyre that introduces Extensions (type-map) to eyre::Report.

This is a simple wrapper around color_eyre with everything equal, and just introduces traits ExtensionExt, Extension for adding and accessing custom data.

To learn more about color-eyre, see their documentation.

TLDR

extension_eyre helps you add extensions of any type to your error like this:

Setup

Add the following to your toml file:

[dependencies]
extension-eyre = "0.1"

And install the panic and error report handlers:

use extension_eyre::eyre::Result;

fn main() -> Result<()> {
    extension_eyre::install()?;

    // ...
    # Ok(())
}

Features

For all the features introduced by color-eyre, please see their documentation.

Adding extensions of any type to error reports via ExtensionExt trait

The crate exposes ExtensionExt trait for adding and Extension trait for accessing extra data to error reports. The extensions implementation is a copy of http crate's Extensions implementation.

ExtensionExt allows adding data of any type to error reports. At the application level, you can access this data with trait Extension with method report.extension_ref::<T>().

use extension_eyre::{eyre::eyre, ExtensionExt, Extension, eyre::Report};
use std::process::Command;
use tracing::instrument;

pub struct Retry;

#[instrument]
fn app(path: &str) -> Result<String, Report> {
    if let Err(err) = read_file("fake_file") {
        if let Some(Retry) = err.extension_ref() {
            // ...handle retry case
        }
    }

    Ok(Default::default())
}

#[instrument]
fn read_file(path: &str) -> Result<String, Report> {
    Command::new("cat").arg(path).output2()
}

trait Output {
    fn output2(&mut self) -> Result<String, Report>;
}

impl Output for Command {
    #[instrument]
    fn output2(&mut self) -> Result<String, Report> {
        let output = self.output()?;

        let stdout = String::from_utf8_lossy(&output.stdout);

        if !output.status.success() {
            Err(eyre!("cmd exited with non-zero status code")).extension(Retry)
        } else {
            Ok(stdout.into())
        }
    }
}

License