主页 / coding / 问题 / 79530902
Accepted
Harry
Asked: 2025-03-24 19:09:34 +0800 CST

根据 Ok 值将结果类型转换为另一种类型

  • 772

我如何才能根据值习惯性地将一种Result类型转换为另一种类型？ResultOk

fn get_res1() -> Result<bool, ()> {
    Ok(true)
}

fn get_res2() -> Result<(), String> {
    let res = get_res1().map_err(|err| String::from("Execution failed"))?;

    // map Ok value to Result type(function return type) based on its value
    // Is it possible to combine the below transformation with the above Result type method map_err?
    if !res {
        return Err(String::from("Operation failed"));
    }

    Ok(())
}
rust

1 个回答

  1. Best Answer

    我认为基本上有三种方法，它们的作用是相同的，只是风格不同。

    fn get_res2_1() -> Result<(), String> {
    let res = get_res1();

    match res {
        Ok(true) => Ok(()),
        Ok(false) => Err(String::from("Operation failed")),
        Err(_) => Err(String::from("Execution failed")),
    }
}

fn get_res2_2() -> Result<(), String> {
    let res = get_res1();

    match res {
        Ok(b) if !b => Err(String::from("Operation failed")),
        Ok(_) => Ok(()),
        Err(_) => Err(String::from("Execution failed")),
    }
}

fn get_res2_3() -> Result<(), String> {
    let res = get_res1();

    res.map_err(|_| String::from("Execution failed"))
        .and_then(|b| {
            if b {
                Ok(())
            } else {
                Err(String::from("Operation failed"))
            }
        })
}
    • 3

相关问题