Error Handling Patterns

Result Match

Handling Success and Failure

Result represents either Ok(value) or Err(error). Matching both cases makes the success and failure paths explicit.

Program

Play the program to parse selected text and build a label from the Result.

result_match.rs 
fn main() {
    let text = ;
    let parsed = text.parse::<i32>();
    let label = match parsed {
        Ok(value) => format!("ok:{value}"),
        Err(_) => "error".to_string(),
    };
    println!("{label}");
}

fn main() {
    let text = ;
    let parsed = text.parse::<i32>();
    let label = match parsed {
        Ok(value) => format!("ok:{value}"),
        Err(_) => "error".to_string(),
    };
    println!("{label}");
}

fn main() {
    let text = ;
    let parsed = text.parse::<i32>();
    let label = match parsed {
        Ok(value) => format!("ok:{value}"),
        Err(_) => "error".to_string(),
    };
    println!("{label}");
}
Result `Result<T, E>` is either `Ok(T)` or `Err(E)`.
match `match parsed` handles both success and error cases.
error path The `Err(_)` arm ignores the error detail and returns a stable label.