Macro rethrow 

macro_rules! rethrow {
    ($result:expr) => { ... };
    ($result:expr, $($args:tt)*) => { ... };
}

Rethrow an Err, optionally with additional context

This is useful if the error path requires additional handling

Prelude import is required to bring in the Context trait.

use cu::pre::*;

fn some_fallable_func() -> cu::Result<String> {
    Ok("foo".to_string())
}

fn main() -> cu::Result<()> {
    // this input is just to show the formatting
    let input: i32 = 42;

    let foo = match some_fallable_func() {
        Ok(x) => x,
        Err(e) => {
            // supposed some additional handling is needed,
            // like setting some error state...

            cu::rethrow!(e, "failed: {input}");
        }
    };

    assert_eq!(foo, "foo");

    Ok(())
}