Rust Programming Cookbook

How it works...

Thanks to Rust's ability to check panic results, we can verify the messages and the fact that the panic occurred. From step 2 to step 4, we are simply panicking using various (common) methods, such as unwrap() (https://doc.rust-lang.org/std/option/enum.Option.html#method.unwrap) or panic!() (https://doc.rust-lang.org/std/macro.panic.html). These methods return messages such as 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:347:21, or panicked at 'explicit panic', src/lib.rs:64:9, which are not easy to debug.

However, there is a variation of unwrap() called expect(), which takes a &str parameter as a simple message for users to debug the issue further. Steps 4 to 6 show how messages and return values are ...