【Rust】结果枚举（三）

环境

• Time 2022-03-25
• Rust 1.59.0

示例

or

fn main() {
    let result: Result<u32, u32> = Ok(44);
    println!("{:?}", result.or(Err(4)));
}

or_else

fn main() {
    let result: Result<u32, u32> = Ok(44);
    let result: Result<u32, u32> = result.or_else(|e| Ok(e * 2));
    println!("{:?}", result);
}

unwrap_or

fn main() {
    let result: Result<u32, u32> = Err(44);
    println!("{:?}", result.unwrap_or(4));
}

unwrap_or_else

fn main() {
    let result: Result<u32, u32> = Err(44);
    println!("{:?}", result.unwrap_or_else(|x| x * 2));
}

unwrap_unchecked

fn main() {
    let result: Result<u32, u32> = Ok(44);
    println!("{:?}", unsafe { result.unwrap_unchecked() });
}

unwrap_err_unchecked

fn main() {
    let result: Result<u32, u32> = Err(44);
    println!("{:?}", unsafe { result.unwrap_err_unchecked() });
}

总结

了解了结果枚举中相关的一些方法。

附录