如何将dbg()重定向到stdout？

Question

有些情况下，stderr是不可用的。是否有一种方法可以让dbg!()打印到stdout，或者有其他命令将与dbg!()相同的信息打印到stdout？

Answer 1

对于另一个命令，复制并粘贴implementation of dbg，将eprintln更改为println，将$crate更改为::std。

macro_rules! dbg {
    // NOTE: We cannot use `concat!` to make a static string as a format argument
    // of `println!` because `file!` could contain a `{` or
    // `$val` expression could be a block (`{ .. }`), in which case the `println!`
    // will be malformed.
    () => {
        ::std::println!("[{}:{}]", ::std::file!(), ::std::line!())
    };
    ($val:expr $(,)?) => {
        // Use of `match` here is intentional because it affects the lifetimes
        // of temporaries - https://stackoverflow.com/a/48732525/1063961
        match $val {
            tmp => {
                ::std::println!("[{}:{}] {} = {:#?}",
                    ::std::file!(), ::std::line!(), ::std::stringify!($val), &tmp);
                tmp
            }
        }
    };
    ($($val:expr),+ $(,)?) => {
        ($(::std::dbg!($val)),+,)
    };
}

fn main() {
    dbg!(1 + 1);
}