expect-exit: display an error message and exit without a panic

The expect-exit library defines the Expected, ExpectedWithError, and ExpectedResult traits and implements them for the standard Result and Option types as appropriate. This allows a program to display an error message and exit with a non-zero exit code without invoking a Rust panic, yet optionally unwinding the stack so that various objects may perform some clean-up actions.

The methods with an _e suffix append an appropriate error message to the supplied one. The methods with a _ suffix allow the caller to specify an already-constructed message instead of a function that returns it.

Example

use expect_exit::{Expected, ExpectedResult};

{
    env::var(name).or_exit(|| format!("{} not specified in the environment", name))

    fs::read_to_string(path).or_exit_e(|| format!("Could not read {:?}", path))

    tx.send(result).await.or_exit_e_("Could not tell the main thread");

    let config = parse().expect_result_("Could not parse the config")?;
    Ok(config.value + 1)
}

For the crate's change history, see the NEWS.md file in the source distribution.

Author: Peter Pentchev <roam@ringlet.net>