14.6 Best Practices

To make the most of Option<T>, keep these guidelines in mind.

14.6.1 When to Use Option<T>

  • Potentially Empty Return Values: If your function might not produce meaningful output.
  • Configuration Data: For optional fields in configuration structures.
  • Validation: When inputs may be incomplete or invalid.
  • Data Structures: For fields that can legitimately be absent.

14.6.2 Avoiding Common Pitfalls

  • Avoid Excessive unwrap(): Uncontrolled calls to unwrap() can lead to panics and undermine Rust’s safety.
  • Embrace Combinators: Methods like map, and_then, filter, and unwrap_or eliminate boilerplate.
  • Use ? Judiciously: It simplifies early returns but can obscure logic if overused.
  • Handle None Properly: The whole point of Option is to force a decision around missing data.
// Nested matching:
match a {
    Some(x) => match x.b {
        Some(y) => Some(y.c),
        None => None,
    },
    None => None,
}

// Using combinators:
a.and_then(|x| x.b).map(|y| y.c)