Errors Are Values

Rust

Replace exceptions with types: `Option`, `Result`, `?` as a `From` conversion, error enums, `Display`/`Error` by hand, and when a panic is the correct answer.

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0 / 19 solved · 5 articles

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1. No null, no exceptions: Option and Result are just enums Read
2. Not solved yet. Matching on Option
3. Not solved yet. The Option combinator vocabulary
4. Not solved yet. Eager vs lazy defaults
5. Not solved yet. Borrowing through Option
6. Not solved yet. Mutating an Option in place
7. Not solved yet. Result, and why it is #[must_use]
8. Not solved yet. Result combinators and map_err
9. Not solved yet. Converting between Option and Result
10. The `?` operator, exactly Read
11. Not solved yet. Propagating with `?`
12. Not solved yet. `?` on Option, and bridging to Result
13. When panic! is correct, and when it is a bug Read
14. Not solved yet. Implementing std::error::Error
15. Not solved yet. From impls: the machinery behind `?`
16. Not solved yet. Error chains and source()
17. Error enums vs Box<dyn Error> Read
18. Not solved yet. Boxed errors and downcasting
19. Not solved yet. Adding context without anyhow
20. What thiserror and anyhow actually generate Read
21. Not solved yet. #[must_use] in depth
22. Not solved yet. Collecting an iterator of Results
23. Not solved yet. unwrap and expect discipline
24. Not solved yet. Documenting failure: # Errors and # Panics

Check yourself

4 questions · one attempt each

These do not count toward finishing the track. They are here to catch the things that are easy to read past.

0 / 4

parse::<i32>() returns Result<i32, ParseIntError>, but the function returns Result<i32, MyErr>. Why does ? compile?

impl From<ParseIntError> for MyErr {
    fn from(e: ParseIntError) -> Self { MyErr(format!("wrapped: {e}")) }
}

fn parse(s: &str) -> Result<i32, MyErr> {
    Ok(s.parse::<i32>()? * 2)
}

Question 1 of 4